Edinburgh Castle is an historic fortress which dominates the skyline of the city of Edinburgh, Scotland from its position on the Castle Rock. Archaeologists have established human occupation of the rock since at least the Iron Age (2nd century AD), although the nature of the early settlement is unclear. There has been a royal castle on the rock since at least the reign of David I in the 12th century, and the site continued to be a royal residence until the Union of the Crowns in 1603. From the 15th century the castle's residential role declined, and by the 17th century it was principally used as military barracks with a large garrison. Its importance as a part of Scotland's national heritage was recognised increasingly from the early 19th century onwards, and various restoration programmes