Castle Sites offers a fascinating and detailed look into the workings of seven fantastic fortresses:

Kaurak Kholzil, a dwarven bastion built into the face of a cliff to protect a rich adamantium mine;

Cloud Keep, the flying fortress of a storm giant clan;

Dragon's Coffin, built to keep an ancient black dragon trapped inside its subterranean lair; plus a walled valley, the ruined castle of a lich, a border fort, and a frontier outpost.

Each entry includes a description of the site's appearance, history, and layout, a detailed floorplan, complete data on the NPCs who live (or died) there, and adventure hooks to draw player characters into the setting.