The Bronze Door by Raymond Chandler

It stood all by itself over against the left-hand wall of the nearly stripped shop. It stood about two feet out from the side wall, on its own base. It was a double door, apparently of cast bronze, although from its size that seemed impossible. It was heavily scrolled over with a welter of Arabic script in relief, an endless story that here found no listener, a procession of curves and dots that might have expressed anything from an anthology of the Koran to the by-laws of a well-organized harem.

The two leaves of the door were only part of the thing. It had a wide, heavy base below and a superstructure topped by a Moorish arch. From the meeting edge of the two leaves a huge key stuck out of a huge keyhole, the sort of key a medieval jailer used to wear in enormous clanking bunches on a leather belt around his waist. A key from "The Yeomen of the Guard"-a comic-opera key.