An adventure for those seeking inspiration, but you can easily flip this PDF to any D&D version or game system. If you need help on conversion, I created this page for such an occasion: Convert Old Dungeons and Dragons Adventures
The Dark Tower of Cabilar is an D&D adventure for 4-8 characters of 4th-7th level. The party should have several fighters and at least one magicuser, thief, and cleric. Magical weapons are required. Note that falling damage is calculated as increasing by 1d6 damage per 10′ fallen.