Temple of Eternal Flame

In some forgotten corner of the Empire of Dercia there is a ruined temple that has been abandoned and forgotten by both time and people for ages. 
The passing and time have cracked the stonewalls of the temple and the stones were weathered, being overgrown with vines and moss that had swallowed the grand pillars over time. The carvings on the temple walls, depicting gods and creatures, whose names had been lost to history were barely visible beneath the layers of nature that were in the process of reclaiming the temple.
Despite the state of the temple, one thing remained unsettlingly untouched: the braziers. They burned, as they always had. Inside the temple when walking past the lit braziers, one would enter a room with a grand altar, atop the altar was a stone basin, large enough to fit a fully grown man, and it was filled with ashes, thick, black and undisturbed ashes. Scholars who had ventured out to the temple to study it speculated that the temple was once the site of sacrificial offerings and that the temple priests had been devoted to a forgotten deity and at some point had given their lives to feed the eternal flames, believing their souls would keep the fires going forever.
Adventures who dared venture into the wilderness around the temple often spoke about the temple, no priests or worshippers called it home, and yet, the fires within the temples' ancient braziers still burned bright, their flames never fading. No one had ever heard stories about when the fires had not been lit. Some adventures told that they had seen faces in the flames.
The locals of course had their stories about why the braziers still were lit, the most common were that a forgotten deity whose presence still lingered in the temple, maintained the flames as a beacon... or warning.
Other stories told about some ancient and unseen prowled within the shadows of the ruins, keeping watch over the flames. The most unsettling thing about the fires was the warmth from them or rather the lack of warmth as the flames gave off no heat.