Observatory of Ili Senir Unu

From the publisher's blurb: The Observatory of Ili Senir Unu is a dungeon for use with Castles & Crusades intended for 4-6 player characters of levels 8-10. An ancient Observatory almost completely lost to history located in the mountain wilds. History says that a cult once made it their home and that the army sent to route them out was swallowed by the darkness beneath it, never to be seen again.