Constantinople became the new capital of the Eastern Roman Empire after the fall of Rome to Germanic tribes in the 5th century. Under the rule of Justinian in the 6th century, the Byzantine Empire reconquered much of the territory once held by Rome. Byzantine culture was influenced by Roman traditions but spoke Greek, and its legal code and architecture, such as the Hagia Sophia, had lasting influence. However, the empire gradually declined due to unrest, plague, and attacks from neighboring powers.