The box measures 22 x 15 x 11 inches, that is 56 x 38 x 28 cm for my European friends.
The box has a number of internal divisions.
The centre row holds all this. Four walled rooms measuring 5 x 5 squares, three walled rooms measuring 10 x 5 squares, a round room measuring 5 x 5 (roughly), a pyramid 5 x 5, fifteen additional floor areas measuring 5 x 5, one with a fish pool and 3 x 3 floor with toothed and horned skull motif.
Every wall has a lift out section in the middle of each 5 square section which can be swapped out for a door.
The open side section of the box holds all the long walled corridors, either 15 x 2 squares or 10 x 2 squares. There are lift out sections for additional doors as desired.
The third section of box has a number of smaller boxes which contain all the smaller bits and pieces, corners etc.
All in all the box holds everything and a wee bit more that you can see in the above picture. The table is 6 x 4 feet. In the immediate foreground are a few boxes holding some of my dungeon figures. These boxes fit neatly inside the 10 x 5 and 5 x 5 rooms for storage. There is still spare capacity for more figures to be stored.
All the walls, floors and doors are made from scrap foamboard (check your local recycling centre) with additional detail made from cardboard. Walls and floors are given a plaster wash and an acrylic paint job before a heavy coat of varnish. The whole setup is made to be handled.
The square grid to which the dungeon is scaled to has 32mm squares. Allowances have to made for lost space when a wall is present down a corridor edge where the squares are a bit smaller. As long as the outside edge of every feature is a multiple of 32mm, usually 160mm or 320mm then everything fits together just fine.