Red Basilica

The "Red Basilica", also called variously the Red Hall and Red Courtyard, is a monumental ruined temple in the ancient city of Pergamon, now Bergama, in western Turkey. The temple was built during the Roman Empire, probably in the time of Hadrian and possibly on his orders. It is one of the largest Roman structures still surviving in the ancient Greek world. The temple is thought to have been used for the worship of Egyptian gods – specifically Isis and/or Serapis, and possibly also Osiris, Harpocrates and other lesser gods, who may have been worshipped in a pair of drum-shaped rotundas, both of which are virtually intact, alongside the main temple.

Although the building itself is of an immense size, it was only one part of a much larger sacred complex, surrounded by high walls, that dwarfed even the colossal Temple of Jupiter in Baalbek.

Source: Wikipedia