"It was a landscape, hanging in space.
There was a squat little house with a garden around it. ...
The Hogfather apparently lived in some kind of horrible slaughterhouse in the mountains, festooned with sausages and puddings and painted a blood red.
Which suggested style. A nasty style, but at least style of a sort. This house didn't have style of any sort. ...
She found the front door. It was black, with a knocker in the shape of an omega.
Susan reached for it, but the door opened by itself.
And the hall stretched away in front of her, far bigger than the outside of the house could possibly contain. She could distantly make out a stairway wide enough for the tap dancing finale in a musical.
[Another room] could have housed a small town.
A small area of carpet occupied the middle distance, no more than a hectare in size. It took Susan several minutes to reach the edge.
It was a room within a room. There was a large heavy-looking desk on a raised dais, with a leather swivel chair behind it. There was a large model of the disc-world, on a sort of ornament made of four elephants standing on the back of a turtle. There were several bookshelves, the large volumes piled in the haphazard fashion of people who're far too busy using the books ever to arrange them properly. There was even a window hanging in the air a few feet above the ground.
But there were no walls. [and] The carpet had a skull-and-bones pattern."
From Soul Music by Terry Pratchett