Church of the Holy Apostles

The Church of the Holy Apostles, also known as the Imperial Polyandrion, was a Byzantine Eastern Orthodox church in Constantinople, capital of the Eastern Roman Empire. The first structure dated to the 4th century, though future emperors would add to and improve upon it. It was second in size and importance only to the Hagia Sophia among the great churches …
The Church of the Holy Apostles, also known as the Imperial Polyandrion, was a Byzantine Eastern Orthodox church in Constantinople, capital of the Eastern Roman Empire. The first structure dated to the 4th century, though future emperors would add to and improve upon it. It was second in size and importance only to the Hagia Sophia among the great churches of the capital.
Data from: en.wikipedia.org