Skaros is the most important attraction in Imerovigli, an impressive rock seen also from Fira. The fortified settlement was presented for the first time in 1421 by the traveller and map maker Boundelmonti. Travellers of the 17th century report that its natural position rendered it impregnable to attacs. The only accurate surviving image of the Imerovigli Skaros is a pencil sketch belonging to Thomas Hope, housed at the Benaki Museum, Athens.
On top of the conic rock, one can see the fortified hub of the settlement, which was connected to the rest of the island via a movable wooden bridge. It was densely populated and had a labyrinth like path system.
As it appears on Skaros there were two castles. The older one, called Epano Kastro (Upper Castle, or Roka) was a fortified citadel on the top of the rock. The more recent one was called Kato Kastro (lower castle), but it suffered from the falling fragments of the rock above.
The older castle was built by Venetian Jacopo Barozzi, to whom Santorini was handed over in 1207. He and his noblemen used it as headquarters and residence. Space economy was what counted most in organising the settlement. The villagers exploited the very limited space to the utmost. Structures were packed tight, built in direct contact to one another. The basic building material was stone, which also served defence purposes.
Kato Kastro was built in the 17th century and people made use of the building materials from the castle of Roka to erect their houses. In 1642, part of the castle was set aside to build the bishop's residence. It was inhabited by Westerners, Catholics and, later on, Orthodox. There were the administration building, the residences of noblemen, the cathedral, churches, and monasteries. The Gyzi family founded here the monastery of Agios Nikolaos (Saint Nicholas).
People started to abandon Skaros in the early 17th century; by the end of the 18th century the transfer was completed. They moved to Fira whice became the new capital of the island. Among the reasons why Skaros was deserted were the hard conditions of living and transport, the destruction from falling rocks and the fact that the danger of pirate raids had ceased.
Today only few ruins of the medieval settlement are still visible on the rock.