 It begins as Dalry Road at the Haymarket, Edinburgh junction with the A8, passing near but not through Lanark and ending as Miller Road in Ayr.Between Edinburgh city centre and Lanark it passes through the Edinburgh suburbs of Slateford, Juniper Green, Currie and Balerno; then Carnwath (where the A70 joins the A721 for three miles), Carstairs (where the two roads separate again), and Ravenstruther, while between Lanark and Ayr it passes through Hyndford Bridge, Rigside, Douglas, Muirkirk, Smallburn, Cumnock, Ochiltree, and Coylton.The Scots name of the road is the "Lang Whang", a whang in the Scots tongue being a narrow strip of leather, usually a long leather bootlace.