The small island about 500 metres (1640 feet) offshore was the site of a Byzantine church dedicated to Agios Theodoros. The Venetians had no use for a church but could use a fortress to protect the harbour approaches. The Italian architect Antonio Gambello designed a hexagonal castle with a tall central tower and parapets for small artillery. Unfortunately, Bourtzi (as the fortress is known) repeatedly failed to protect Nafplion. In 1540, it took the Ottomans three years to prevail, but eventually, they did, destroying the town along the way. The most disastrous failure came in July 1715 when the Ottomans came back. Their fleet blockaded the harbour and bombed the city, ignoring Bourtzi much like an elephant will ignore a fly. The seaward walls seemed to hold, but the cowardice of the Venetian soldiers defending the castle on the hill above Nafplion (Palamidi) sealed the town's fate.