Stephen King's The Dark Tower: The Door.

The Dark Tower II. The Drawing of the Three.
The Prisoner.
Chapter 1. The Door. 4.

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It stood six and a half feet high and appeared to be made of solid ironwood, although the nearest ironwood tree must grow seven hundred miles or more from here. The doorknob looked as if it were made of gold, and it was filigreed with a design which the gunslinger finally recognized: it was the grinning face of the baboon.

There was no keyhole in the knob, above it, or below it.

The door had hinges, but they were fastened to nothing - or so it seems, the gunslinger thought. This is a mystery, a most marvellous mystery, but does it really matter? You are dying. Your own mystery - the only one that really matters to any man or woman in the end - approaches.

All the same, it did seem to matter.

This door. This door where no door should be. It simply stood there on the gray strand twenty feet above the high-tide line, seemingly as eternal as the sea itself, now casting the slanted shadow of thickness toward the east as the sun westered.

Written upon it in black letters two-thirds of the way up, written in the high speech, there were two words:

THE PRISONER