Giantskeep

Enormous giantish citadel on an island in the Caltsee built by Gornningr, the first Storm King. Following the giants' retreat after their defeat in the War of the Elves and Giants, the citadel was occupied by mannish troops from the new Kingdom of Sigsland . Their leader became the first Duke of Hogenstaff.
The current duke, Marten, Duke of Hogenstaff, is reputed to be a pirate.
While the citadel itself was built by (stone) giants and is enormous in every dimension, the giants' smaller servants, slaves and escaped prisoners built a secret city beneath the citadel. In the centuries since the giants' departure, this secret city has been developed further. It is now a thriving (and quite wealthy) community of several thousand people - mostly men, with some gnomes, halflings, dwarves and other races.