Nendrum Monastery may have been founded in the 5th century, but this is uncertain. The monastery came to an end at some time between 974 and 1178, but its church served a parish until the site was abandoned in the 15th century. Some remains of the monastery can still be seen.
Dendrochronology has dated a tide mill on the island to the year 619, making this the oldest excavated tide mill anywhere in the world. The monastic site included orchards, gardens, pastures, arable fields, and a guest-house.
The principal monastic remains which can now be seen are three concentric cashels (enclosures) of dry stone walling, but these were substantially rebuilt by Lawlor in the 1920s. The central cashel has the round tower remains, a ruined church with a sun-dial, and a graveyard. The second cashel contains what is called a 'monastic school' or workshop and other burials.
The canonical sundial now seen at one corner of the ruined church was reconstructed from fragments found during the excavation of the site in 1924 and has been dated to about the year 900. One of only a few early medieval sun-dials known to exist, it takes the form of a vertical stone pillar, 190 cm high, 40 cm wide and 15 cm thick, with the dial and gnomon on one face at the top. However, because of the nature of the reconstruction, the original height of the pillar is conjectural.
Angelokastro is a Byzantine castle on the island of Corfu. It is located at the top of the highest peak of the island"s shoreline in the northwest coast near Palaiokastritsa and built on particularly precipitous and rocky terrain. It stands 305 m 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.
Angelokastro is one of the most important fortified complexes of Corfu. It was an acropolis which surveyed the region all the way to the southern Adriatic and presented a formidable strategic vantage point to the occupant of the castle.
Angelokastro formed a defensive triangle with the castles of Gardiki and Kassiopi, which covered Corfu"s defences to the south, northwest and northeast.
The castle never fell, despite frequent sieges and attempts at conquering it through the centuries, and played a decisive role in defending the island against pirate incursions and during three sieges of Corfu by the Ottomans, significantly contributing to their defeat.
During invasions it helped shelter the local peasant population. The villagers also fought against the invaders playing an active role in the defence of the castle.
The exact period of the building of the castle is not known, but it has often been attributed to the reigns of Michael I Komnenos and his son Michael II Komnenos. The first documentary evidence for the fortress dates to 1272, when Giordano di San Felice took possession of it for Charles of Anjou, who had seized Corfu from Manfred, King of Sicily in 1267.
From 1387 to the end of the 16th century, Angelokastro was the official capital of Corfu and the seat of the Provveditore Generale del Levante, governor of the Ionian islands and commander of the Venetian fleet, which was stationed in Corfu.
The governor of the castle (the castellan) was normally appointed by the City council of Corfu and was chosen amongst the noblemen of the island.
Angelokastro is considered one of the most imposing architectural remains in the Ionian Islands.