Aggelokastro is one of the most important Byzantine castles in Greece and one of the oldest. It was already there since the 7th century.

It is located on the island of Corfu at the top of the highest peak of the island's shoreline in the north coast near Palaiokastritsa and built on particularly precipitous and rocky terrain. It stands 305m on a steep cliff above the sea and surveys the City of Corfu and the mountains of mainland Greece to the southeast and a wide area of Corfu toward the northeast and northwest.

The origin of its name is not completely clear, with some historians mentioning that in 1214 Michael I Komnenos Doukas, Despot of Epirus, sometimes called Michael Angelos, annexed Corfu to Epirus and following his death, Michael II Komnenos Doukas, his son, further fortified the area and named it after himself and his father: "Angelokastro".

The Despots were related to the Komnenoi dynasty of Byzantine emperors.

Today, the tourist signs in the area refer to it, wrongly, as St. Angelo's castle.