Hagia Irene is located in the outer courtyard of the Topkapi Palace in Istanbul, and its name means "Holy Peace." It is the oldest church in the Eastern Roman (Byzantine) Empire. It was also the second largest church in Istanbul after Hagia Sophia, and after the burning of the Hagia Irene church built by Constantine. It was rebuilt by Justinian in the sixth century, and the work was completed by Emperor Constantine V in the eighth century, and it was decorated with a simple mosaic cross. .