Skull of Lysander is probably one of the first fan missions for Thief 1 that I have ever played (hence, for nostalgic reasons, my rating is rather high). Garrett has been hired to retrieve from a wizard's fortress a magical item called The Skull of Broca. Skull of Lysander is a short mission that you can finish in 25-30 minutes. While one shouldn't expect any architectural or gameplay marvels, this heavily-guarded wizard's residence has a typical Dark Project atmosphere of sneaking through dim and narrow stone corridors and staircases. Skull of Lysander contains a few interesting and funny readables, there are also some simple yet nicely done SFX effects. Overall, quite enjoyable for a level from 1999.

PS: The mission should ideally be played with a .dml bug-fix downloaded from TTLG: https://www.ttlg.com/forums/showthread.php?t=136764