In the old city centre close to Hagia Sophia and the hippodrome there was also a great open courtyard with an attached basilical hall that served as a market place. This courtyard probably goes back to the time of Constantine the Great. In the time of Justinian I the eastern portico was destroyed when the Hagia Sophia burned down in 532. Before this portico was restored, the opportunity was taken to built in a vast cistern under the courtyard with a vaulted roof resting on 336 columns. Whereas the Basilica has disappeared completely, the cistern survives under the name of Yerebatan Sarayi (the Sunken Palace).