Castle Kensek is the capital of the Kingdom of the Drow, and home of its current ruler. The castle itself is actually more like that of a large citadel, built into the peak of a small mountain near the border between the Elven Realm and the Northern Wastes.
Castle Kensek was constructed early in the history of the Drow Kingdom, as ordered by then-King Kensek. Newly elected as the King of the Drow by the various Drow houses of the time, he brought up the idea of a fortress for which the Kings and Queens could live and rule in. The other Drow houses agreed, and construction began on such a fortress.
The castle was finished ten years later, and additional parts were added on over time by future Kings and Queens of the Drow. There were also parts added on by the various Drow houses, with the intent of aiding the King or Queen in their endevours (or as ways to seek favor with the ruler of the time.)
The Castle as it stands now is a sprawling citadel, massive in size and almost the size of the mountains around it. Numerous Royal Guard squads patrol the interior, while the fortress is protected outside by an extremely large garrison of troops stationed just inside the third defensive wall. Deep inside the main tower live the King/Queen, as well as their advisors.