Dun Ara was a stronghold of the MacKinnon clan who held the land here from 1354 onwards. The castle was still in use until the 17th century when it was abandoned. The castle was probably built on the site of a previous Dun or fort. The castle had a surrounding wall protecting a central keep or building on the main outcrop of rock. The location was valuable as it protected a harbour of boat landing as well.
The castle was fortified by enclosing the entire rock summit with a curtain-wall of stone and lime, which varies from about 1.3 m to 1.8 m in thickness. It is best preserved on the north-east side, where it rises to a maximum height of 1.8 m, but little remains on the south-west and south-east sides. The masonry was built with coarse, lime mortar, much of it has washed out of the facework giving it the appearance of dry-stone walling. It is possible that in places the lower courses of masonry pre-date the medieval castle and belong to an earlier fort that occupied the same site. The entrance is on the south-east side.
References:The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.