The Church of St George is an Early Christian red brick rotunda. It is the oldest building in Sofia and is located in the garden of the Presidential Palace. The Rotunda was built in the 4th century AD. It is believed that it was built on the site of an old pagan temple. It is famous for the frescoes dating from the 12th - 14th centuries . In the church were kept the holy relics of the patron of Bulgaria – St. Ivan Rilski, before being stolen from the Hungarians in 1183. During the Ottoman rule the church was transformed into a mosque.