This is a landmark and one of the most photographed sights in Nafplio. The Bourtzi fortress is located off-shore in the middle of the town's port and was built by the Venetians for protection in 1473. Italian architect, Antonio Gambelo, undertook the construction, which was completed by the engineer, Brankaleone.

The center of the fortress is a three-storey tower from where communication took place by means of ladders. Over the years it has undergone several modifications as the Turks built an underwater stone barrier, while in the 18th century the Venetians raised the central tower resulting in most of the islet being covered with fortifications.

During the Greek Revolution, Bourtzi was called Kasteli or Sea Tower from where the Greek government fled in 1826. It was used as a fortress until 1865 and subsequently became the residence of executioners who undertook their executions of the death row prison of Palamidi.

Note that in 1935, after conversion by the German architect, Wulf Schaeffer, Bourtzi was converted into a hotel.