You can pretty much assemble dungeons and Fortresses from a bunch of random Rooms. 
1. Library of Pain
Dimensions: Circular (10' diameter), 100 feet High Roof, Exits at top and Bottom of Stairs.
Description: 3 feet wide Iron Spiral Staircase descends down the Walls of the Room with a Bookshelf Tower up the Core. The Books are blank - yet bound in Human Skin.
Dimensions: large circular (15 squares), domed roof
Description: The walls of this temple are covered in a fine pulsing tracework of red lines, the floor is a shallow (~3in, possibly slipping hazard but not otherwise difficult terrain unless being manipulated by a priest of the temple) pool of blood, at the centre of which is a stone altar on which sacrifices are made. The ceiling is covered in still beating hearts, beating in sync to produce an almost deafening thudding
Dimensions: Circular room, (10' diameter), 5 squares to the ceiling
A warm, idyllic room with columns littering the walls, as if supporting a ceiling or structure above. A worn down ladder hangs in the northeast, once reaching all the way down to the floor, now broken off halfway. In the middle of the room stands a drystone altar, covered with dried blood. Between the columns, the walls are covered in lively murals of people in varying stages of love, running all the stages from meeting someone, to deceit and murder, if you follow the images full circle.
Edit: Exits are through the ladder you need to jump/climb to, and a door splitting the hate/love murals in the wall.
community.wizards.com/go/thread/view/758...