World Heritage Sites in Scotland are locations that have been included in the UNESCO World Heritage Programme list of sites of outstanding cultural or natural importance to the common heritage of humankind. Historic Environment Scotland is responsible for 'cultural' sites as part of their wider responsibility towards the historic environment. The Environment Directorate is responsible for natural sites. There are currently six sites in Scotland, with a further two undergoing a process of formal evaluation. Informal discussion of a site for "Þings" (Norse parliaments) has taken place. Existing sites The six existing sites are mapped to the right and described in detail below. They are: St. Kilda Edinburgh Old Town and New Town The Heart of Neolithic Orkney New Lanark The Antonine Wall The Forth Bridge St. Kilda is a small, out-lying archipelago of Hebridean islands which was inscribed as a "natural" site in 1986. In 2004, the site was extended to include a large amount of the surrounding marine features as well as the islands themselves. In July 2005 it became one of the few World Heritage Sites to hold joint status for its natural and cultural qualities. The islands were bequeathed to the National Trust for Scotland in 1957. They are also a Biosphere Reserve and a National Scenic Area. "Edinburgh Old and New Towns" were together inscribed as a World Heritage Site in 1996. The former includes the medieval Royal Mile which runs from Edinburgh Castle to the Palace of Holyroodhouse, and is bordered to the north by the neo-classical 18th century "New Town" which includes Princes Street. It is managed by the Edinburgh World Heritage Trust. "The Heart of Neolithic Orkney" includes Maeshowe, the Ring of Brodgar, Skara Brae, the Standing Stones of Stenness and other nearby sites. It was inscribed in 1999 and is managed by Historic Scotland. New Lanark was inscribed in 2001. It is a restored 18th century industrial cotton mill village in South Lanarkshire constructed by Robert Owen as an experiment in utopian socialism. Restoration was organised by the New Lanark Conservation Trust, which was formed in 1974. The Antonine Wall was inscribed in July 2008. It is an extension to a wider series of sites in Austria, Germany and Slovakia entitled "Frontiers of the Roman Empire". The Wall is the remains of a defensive line made of turf c. 20 feet high, with nineteen forts. It was constructed after 139 AD