The Entrance to Hades??

 

Actually, No.

Closer inspection reveals that it's the entrance to the Grosvenor Hotel, and it's Ballroom (on Floor 2A).

While utterly tedious, there is the mystery of where this Grosvenor Hotel actually is. The obvious candidate in London is actually The Grosvenor House Hotel.

Bonus - For those who missed it yesterday, Titanic With A Cat.

Standing At The Crossroads...

...waiting to do a deal with Mr Scratch.

One of the geekiest part of this hobby of mine, possible geekier that the the original photographer photographing roadsigns in September 1975, is trying to find the exact location of slides.