St. Mark's Basilica, situated on the eastern end of St. Mark's Square, serves as the cathedral church for the Archdiocese of Venice and holds the relics of Saint Mark the Evangelist, the city's patron saint. The basilica is connected to the Doge's Palace, a Venetian Gothic structure dating back to 1340. It once served as the residence for the Duke of Venice and later as a prison before being converted into a museum in 1923.