The Radiant Citadel

Adapted and inspired from WotC's Journey's through the Radiant Citadel.
Gathering Place of Strangers and Stories
Against the unending mist and unseen terrors of the Ethereal Plane, the Radiant Citadel stands bright as a bastion of hope. It's a living relic of the ingenuity and collaboration of twenty-seven great civilizations. Abandoned and lost for ages, the Citadel was resurrected from its slumber and reclaimed by descendants of those societies, though some peoples remain missing. The city serves as a nexus of diplomacy and trade, a repository of histories and secrets, and a thriving sanctuary for those seeking safety or a better life.
The Radiant Citadel is a miracle of architecture, a floating city carved out of a single, massive fossil that snakes around a colossal gemstone shard known as the Auroral Diamond. The luminescence of the Auroral Diamond is mirrored in the constellation of fifteen structure-sized gemstones, the Concord Jewels, which orbit the city and provide transportation to the far-flung homes of the Citadel's founding civilizations. In the haze of the Ethereal Plane, the Auroral Diamond is a scintillating beacon visible from leagues away. The diamond itself seems to have moods, changing colors unpredictably, but it is always visible for wanderers lost and in need. Just beyond the city whirls a massive, ever-threatening, ethereal cyclone known as the Keening Gloom - a looming threat that's a grim reminder of the Citadel's precarious position.
Heroes and paupers meet on equal footing in the Radiant Citadel. By common agreement, power and resources are equitably shared. Dignity is afforded to all, and great need is met with great aid.

Features

Those familiar with the Radiant Citadel know the following details:
Hallmarks. The Radiant Citadel is an extraplanar refuge known for its collaborative society and ecological beauty. Local traditions of oral storytelling preserve ancestral wisdom from many worlds.
People of the Radiant Citadel. The majority of the Radiant Citadel's populace comes from the civilizations that govern the city. This makes the population an ethnically diverse mix of humans, dragonborn, dwarves, elves, gnomes, and halflings, along with a variety of other races.
Languages. Common is widely known, along with dozens of other languages.

Noteworthy Sites

The Radiant Citadel is a testament to a lost age of extraordinary magic and mythical beasts. The city rises from a gargantuan fossil, and every road and building has been carved from it. The Citadel is a place of beauty and wonder, with a vast array of vegetation and a multitude of sites and inhabitants.

Auroral Diamond

The Auroral Diamond is the heart of the Radiant Citadel. A massive gemstone of unfathomable power, its life-giving magic runs through the entire city; the city's vegetation, water, light, and unique artifices depend on the Diamond.
The Auroral Diamond changes color for unknown reasons. Sometimes it holds a color for an entire year, while other times it shifts twice in a single week. Rarely does it ever repeat a color. Some scholars believe each color represents the birth of a new civilization somewhere in the multiverse, and repetition of a color means the death of that civilization. Other scholars hypothesize the changing colors are a countdown to some unknown event.
The Auroral Diamond is indestructible. Whatever magic hollowed out the gemstone's center and created the Preserve of the Ancestors (described later) is unknown.

Court of Whispers

The denizens of the Court of Whispers barter for current knowledge. Heralds, criers, bards, and griots buy and sell information from the fifteen founding civilizations active in the Citadel, as well as other lands. Skilled scouts and spies can also be hired for short-term reconnaissance or long-term infiltration. The Court is a mixed outdoor-indoor space with quiet alcoves and open plazas, and plentiful work is available here for talented adventurers.
The Speakers for the Ancestors - the leaders of the Radiant Citadel - employ freelancers from the Court of Whispers to keep track of major concerns in their people's homelands, as well as potential threats to the Citadel, while the Shieldbearers of the Citadel (see the "Palace of Exile" section) seek information so they can identify crisis points where their operatives are needed. Even common citizens might hire folk from the Court to find missing loved ones, locate lost family treasures, or gather information on rivals.
Powerful organizations and individuals from across the planes send agents to the Court of Whispers to collect information and do business on their behalf. Noteworthy examples include the Harpers of Abeir-Toril, Sigil's Fraternity of Order, and agents of the planes-traveling gnome fixer Vi.

House of Convalescence

The House of Convalescence focuses the life-giving energies of the Auroral Diamond, allowing for incredible feats of healing magic. This makes the House of Convalescence an oasis for the sick, the injured, and the desperate. It also draws clerics and healers of many traditions. Most come to serve those in need, but some seek to understand the magical properties of the place itself.
Magic is affected in the following ways in the House of Convalescence:
Diamond Components. When the spells raise dead, resurrection, revivify, or true resurrection are cast in the House of Convalescence, a diamond material component is never required.
Hit Point Maximum. When creatures would normally roll one or more dice to restore hit points with a spell, they instead use the highest number possible for each die. For example, instead of restoring 2d6 hit points to a creature, a spellcaster restores 12.

The Keening Gloom

Just beyond the light of the Radiant Citadel rages the Keening Gloom, a massive ethereal cyclone. Nothing that enters the cyclone is seen again.
When explorers rediscovered the Citadel, the Keening Gloom hungrily circled the city. Its endless howl struck terror in their hearts and engulfed several adventurers. After the heroes entered the Citadel and reawakened its power, the cyclone was driven back. But in times of turmoil within the Citadel, the cyclone ominously draws closer.
Scholars have studied the Keening Gloom for decades but have only theories about its nature, its connection to the Radiant Citadel, and what befalls those caught in its terrible throes. Many fear the cyclone cannot be held at bay forever.

Palace of the Exile

The adventurers who discovered and reoccupied the Radiant Citadel were from the civilizations that founded the city long ago. Among them, several had been set on the path of adventure after conflict or disaster drove them from their homes, and the Citadel provided solace. In turn, they established the Palace of Exile to help others in need.
The palace was named in honor of Socorro the Exile, its founding leader. He was a refugee of war in the land of San Citlán, and he selected one of the most beautiful complexes in the Citadel to house the needy as they arrived. He swore that while his homeland was occupied, he would be an exile and would make his home in the Palace, alongside any others with nowhere else to go.
The Palace of Exile has spacious living quarters with adjoining gardens and recovery centers, where refugees are cared for physically, mentally, and emotionally as they make the transition to either living in the Radiant Citadel permanently or relocating to a new land. The Palace's staff coordinate with the House of Convalescence to provide the best possible aid to the sick and wounded.
The Shieldbearers, the Radiant Citadel's dedicated search-and-rescue force, are headquartered at the Palace of Exile. Where there is a need, the Shieldbearers help.

Preserve the Ancestors

The Preserve of the Ancestors is a sprawling, domed wilderness cut into the heart of the Auroral Diamond. Lush vegetation grows directly out of the diamond, and the expanse is dotted with jackalberry trees, whistling thorn, and zebrawood. Insects, small birds, and the occasional hare make their home here. In the center of the Preserve is a circular, in-ground amphitheater that serves as the meeting place of the Citadel's ruling council, the Speakers for the Ancestors.
While the Preserve has little indigenous wildlife - mostly birds and small mammals - a sect of druids frequently brings injured animals here to be healed and rehabilitated. The Preserve is where the druids keep animals that can no longer survive in their native habitats, creating a menagerie of rare creatures from across many worlds.
Drawn by the power of the Auroral Diamond, spirits from countless lands make their home in the Preserve. Spirits from the same lands or of similar origins inhabit tiny jewels and assemble into amalgamations known as Incarnates. Some are small collections of spirits, but the greatest - related to the citadel's founding civilizations - are larger-than-life beings that embody the wisdom of ages (see the "Incarnates" section for details).

Trade Discal

Encircling the Auroral Diamond, the Trade Discal is a massive marketplace designed so that the founding civilizations could trade on equitable terms. It serves the needs of cities and nations or major trading companies, rather than individual sellers or producers, which is enforced by its high taxes and fees. Large quantities of goods, such as entire herds of animals or tons of metal ore, can be transported via the Concord Jewels (described below) to the Trade Discal quickly and safely.
The Trade Discal is a vital outlet; if something were to happen to it, the impact would be severe for both the Radiant Citadel and the civilizations that depend on it. Adventurers are sometimes hired to oversee the transport of commodities to and from the Citadel or to negotiate on behalf of a major trading company or government. Normally this is a smooth process, but when large amounts of gold are involved, trade is never risk free.

Concord Jewels

Beyond the Radiant Citadel drift the Concord Jewels, which connect the city to its founding civilizations. Each Jewel is a building-sized vessel capable of holding hundreds of people and tons of goods. Though the Jewels take a variety of shapes, their interiors are similar. A cylindrical core holds containers for goods, including livestock. Surrounding the core is seating for passengers. The Citadel employs official operators called Clavigers to pilot the Jewels.
Each Concord Jewel is linked to one of the civilizations that founded the Radiant Citadel. A Jewel unerringly travels between the Radiant Citadel and the homeland of the Jewel's linked people. Even if the Jewel's people have migrated to another world on the Material Plane, the Jewel finds its way to their current home.
While not in use, the Concord Jewels orbit the Radiant Citadel in an incandescent constellation. Each Jewel corresponds to one of the founding civilizations and resembles a giant gemstone of the type noted for that civilization on the Concord Jewels table. Missing civilizations and their Jewels are not listed and can be detailed as you please.

Life in the Citadel

The Radiant Citadel is a city of immigrants. Several of the explorers who reclaimed the Citadel were refugees who escaped hardships that plagued their lands. They chose the Citadel as their home, despite its strangeness and the surreal surroundings of the Deep Ethereal, as it presented an opportunity to start anew. Most of the city's current inhabitants are descendants of the fifteen founding civilizations active in the Citadel, but all are welcome.
Some find living in the Deep Ethereal too disquieting to stay or chafe at the confines of the Citadel. Others depart out of fear that the Keening Gloom will destroy the Citadel. Their numbers are replenished by new arrivals who seek a different life, want to study the city's lore, or find solace in the city's peace and safety. The Citadel's society is shaped by this ebb and flow. Traditions, customs, and values are a mix of old and new; while some adhere to rituals no longer followed in their homeland, others create their own novel practices.

Art and Culture

The Radiant Citadel's diaspora communities constantly learn and borrow from one another, creating a culture unique to the city. This evolution is displayed in the art, the clothing, the music, and - perhaps mostly vividly - the food of the city. While cantinas, tea houses, and eateries serve food and drink from specific communities, the most popular cuisines are fusion dishes like couscous infused with habanero and saffron, panela-coated fried yams, and kimchi tacos.

Diplomacy

Relationships between the Radiant Citadel and the founding civilizations are often shifting. The Citadel sends diplomats abroad and houses embassies from foreign governments, but this goodwill is not always reciprocated. The Citadel's uniqueness makes it a target of foreign actors who seek to exert subtle or overt control over it. At the same time, political activists, dissidents, and revolutionaries seek to exploit the city's neutrality to their advantage, even staging incursions against their home governments from the relative safety of the Citadel.

Governance and Politics

The Radiant Citadel is governed by a council known as the Speakers for the Ancestors. Each Speaker is a descendant of one of the founding civilizations currently known to the Citadel. They are chosen by their community and affirmed into office by the wise and ancient Dawn Incarnates. The Speakers for the Ancestors meet openly in the amphitheater in the center of the Preserve, and Citadel residents often watch their debates. All laws and major decisions of the city are decided by majority vote of the Speakers. Debates can become heated; because each Speaker represents very different constituents, consensus and compromises might take days or even months to reach. Those citizens of mixed ancestry or unconnected to the founding civilizations can choose a Speaker for the Ancestors to represent them. They register with the Speaker's office, and from then on, participate in future elections for that Speaker.
Governance is public, transparent, and participatory. Laws are not static but evolve to meet new challenges and needs. Subcouncils and committees manage the city under the guidance of the Speakers. Complexities persist in governing a highly diverse city with varied customs, beliefs, and social norms, but robust civic engagement helps the city overcome adversity.

Law Enforcement and Justice Public safety and peacekeeping are administered through a variety of councils and organizations designed to address specific issues. The House of Convalescence helps those living with mental illness, while inspectors investigate nonviolent crimes and use nonlethal methods of detainment. Theft is uncommon in the city, and rehabilitation and restorative justice are preferred methods of addressing wrongs. Highly trained local guards mobilize to handle the rare incidents of violence, and citizens are expected to proactively intervene if needed. The worst offenders are sentenced to a controversial Djaynaian punishment wherein the criminal is subjected to a ritual that prevents them from repeating their crime and then is banished from the city.

Lifestyle and Society

Denizens of the Radiant Citadel strive to sustain an egalitarian society. Every citizen is entitled to a basic income that affords them the necessities of living and dignity in lifestyle. Food, water, and green spaces are equally accessible throughout the city. The House of Convalescence turns no one away; healing is priced according to one's means, and the poorest are served without charge. All housing is public, distributed, and administered through the city's councils.
Since the city's resources are limited due to the Citadel's relatively small area and its strange nature, foodstuffs and other materials are carefully conserved, and goods are reused or recycled when possible. Similarly, most food is vegetarian and is grown in green spaces throughout the city. Whether served in a home or an eatery, most animal products must be imported and so are subject to high tariffs.

Tariffs and Taxation

Taxes are progressive to help reduce the gap between the most affluent and the poorest. High tariffs on imports keep the public coffers full, but the Speakers lower or remove tariffs for civilizations in trouble. Similarly, visitors to the Radiant Citadel pay a toll to enter. Those who come with nothing except good will pay no fee. Those with big pockets and big hearts give more according to their conscience rather than risk the rebuke of the city's guards. Rich and poor alike can instead offer something unique that might be to the liking of the Incarnates, such as a lost song, a secret tale, or a rare piece of art. Those who choose this option may present their gift to the Dawn Incarnate of their choice. If their toll is accepted, the visitor is allowed to stay in the Citadel.

Entering the Citadel

Most visitors come to the city by passage on one of the Concord Jewels. However, it's possible to find the Citadel through exploration of the Deep Ethereal. The Auroral Diamond acts like a beacon for the lost and hopeless, and many who seek the Radiant Citadel within the Deep Ethereal find their way there within a few days of searching.
There is only one official entrance to the Radiant Citadel: the Passage of Respite. The Concord Jewels dock adjacent to it, and people using other means to travel to the city are directed by guards to enter through it.
At any time, six guards are stationed at the Passage of Respite. They are led by a mage responsible for accepting tolls. These guards often employ magic items, such as helms of telepathy, when suspicious of the motives of a visitor. A priest from the House of Convalescence also attends the gate, ready to assist the ailing.
It's possible to bypass the Passage of Respite by teleporting or flying into the city, but anyone caught doing so faces massive fines, and repeat offenders risk banishment.