Published by Judges Guild.
Purchase PDF at RPGNow. (Sadly, not the original but a remake aimed at 3.x)
Tegel Manor vexes me.
First published in 1977 and revised in 1980 (and expanded in 1989) by Judges Guild, Tegel Manor is without a doubt one of Bob Bledsaw’s masterpieces. Describing a sprawling 240-room haunted castle, the module is a textbook example of a funhouse dungeon, utterly lacking in anything resembling an ecology and filled with many encounters for which the adjective “whimsical” is charitable at best. The contents and/or inhabitants of each room are random — in some cases literally — meaning that, here you might find nothing more threatening than some giant beetles but next door you might find a Type III demon polymorphed as a kindly old beggar.
Read the Full Retrospective/Review at Grognardia.