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),[1] and Ravenstruther, while between Lanark and Ayr it passes through Hyndford Bridge, Rigside, Douglas, Muirkirk, Smallburn, Cumnock, Ochiltree, and Coylton.

Because the wind enjoys an easy and uninterrupted passage over its length, in winter the road is frequently closed by snow, even by modest snowfalls.

The road passes elevated farmland and grouse moor and presents extensive views over central Scotland to the north.

It was one of the roads along which the murderers Burke and Hare brought the cadavers of their victims for the Edinburgh Medical College to dissect.

Several months later the pair underwent hypnotic regression and claimed to recall that they had been abducted, examined and communicated with by alien creatures.