Perched upon an extinct volcano, Edinburgh Castle is an ancient fortress which dominates the sky-line of the city of Edinburgh, and is Scotland's second most visited landmark, after the Kelvingrove Art Gallery and Museum in Glasgow. Human habitation of the site is dated back as far as the 9th century BC. As it stands today though, few of the castle's structures pre-date the 16th century, with the notable exception of St Margaret's Chapel, the oldest surviving building in Edinburgh, which dates from the early 12th century.
As with all castles, Edinburgh's fortress has been a centre of military activity. As an ancient fortress, Edinburgh Castle is one of the few that still has a military garrison, albeit for ceremonial purposes, and is the official headquarters of the Royal Regiment of Scotland and 52 Infantry Brigade. Sentries still stand watch at the castle gatehouse between 6pm and 9am, with responsibility for guarding the Honours of Scotland.