Historic Scotland & National Trust for Scotland places in South Lanarkshire

Scotland's only preserved gasworks, which lit Biggar from 1839 to 1973, complete with retorts, purifiers, gasholders and the gasman's house; free, closed for the winter, reopens Saturday 3 April 2027 at weekends.

Vast 13th-century castle of enclosure above the Clyde, with the shell of a mighty round donjon besieged by Edward I in 1301 and the Black Douglases' great hall; adult £4.50 while works continue, half price in the first EH year.

The fenced ruin of a hidden Hamilton castle of the 1500s above the Avon gorge in Chatelherault Country Park, Hamilton, among oaks of the 1400s; free, seen from outside only, a walk from the visitor centre.

The grassy mound of a medieval motte castle above a crossing of the River Clyde at Wolfclyde near Biggar; free and open at all times, with steps up from the roadside.

The mausoleum of the Black Douglas earls in Douglas, South Lanarkshire, with three canopied tombs and a clock of 1565 said to be Mary, Queen of Scots' gift; free, interior by arrangement on 01555 851 657.

Museum, Georgian farmhouse and 1950s working farm outside East Kilbride, with Scotland's largest tractor collection and a tractor-trailer ride to the animals.