Porta Alchemica

The Alchemical Door, also known as the Alchemy Gate or Magic Portal, is a monument built between 1678 and 1680 by Massimiliano Palombara, marquis of Pietraforte, in his residence, the villa Palombara, which was located on the Esquiline Hill, near Piazza Vittorio, in Rome. This is the only one of five former gates of the villa that remains; there was a lost door on the opposite side dating them to 1680 and four other lost inscriptions on the walls of the mansion inside the villa.

Source: Wikipedia