After centuries of being an important city, a series of events conspired to cause the downfall of Ephesus. It lost religious importance during Byzantime times when Constantine the Great declared Christianity the official religion of all of Rome. Constantinople, rather than Ephesus, became capital of the Roman Eastern Empire. On top of this, Ephesus had been an important port city. However, that port was now silting up and ships could no longer dock to offload or take on cargo. After raids and earthquakes and a now silted harbour, trade died at Ephesus. The city was finally abandoned in the 15th Century.