Portal

Portal (noun): a door, gate, or entrance, especially one of imposing appearance, as to a palace.

The side view of the entrance to the Russian State Library.  Founded in 1862, its holds the 4th largest collection of books in the world, and was named (and un-named) the "State Library of the USSR in the name of  V. I. Lenin" between 1925 and 1992. Some years ago, I tried to photograph its magnificent interior but got stopped by the security guard. They now run excursions so I might try again.