The UK government's nomination for World Heritage status was announced this week by the UK Culture Secretary. As widely expected, the site being put forward to the conservation body Unesco is the Roman Antonine Wall, which runs for 37 miles across central Scotland from Old Kilpatrick on the river Clyde to Bo'ness on the Firth of Forth. The wall was built around 140AD, in the reign of Emperor Antonius Pius, to deter warriors from the north invading southern Scotland. But it lasted only 25 years, after which the Roman occupying force retreated to behind Hadrian's Wall, across northern England. Unesco will examine the proposal and will make a pronouncement at a later date.