The Cumnock Burn comes from the east. Muick Wattir comes through the town from the south-east. The River Doon (immortalised by the poet Robert Burns in his song "Ye Banks and Braes o` Bonnie Doon") itself comes down from Loch Doon through the Ness Glen, and the river widens temporarily into the Bogton Loch just west of the town. Dalmellington is built partly on the end slopes of the spurs separating these valleys, and partly on the flat ground below.
There has been speculation about the town`s name with some believing that it was a corruption of Dame Helen`s Town. However it is more likely to have derived from the Gaelic dael meallain tuinn "the fort of assembly of the moat-surrounded mound", or more literally "the meeting place at the mound with a Motte". This would connect the place name with the remarkable Motte hill which is still one of the striking features of Dalmellington. Mottes were originally fortified sites on which timber castles would sit and date back to the Anglo-Norman Period around the late 11th and early 12th centuries. Dalmellington Motte has now been officially classed as an Ancient Monument, which will aid its preservation.
The village of Dalmellington grew dramatically after 1847 when the Dalmellington Ironworks constructed furnaces and pits at Waterside. Coal was also mined here and there are still miners cottages, as well as a weaver`s cottage which are open to the public. Today there is no heavy industry but there are steam and diesel locomotives open to the public at the Scottish Industrial Railway Centre.
Nearby Loch Doon has seven miles of water surrounded by moody hillsides amidst spectacular scenery.
A 14th Century castle, now in ruins, was once in the middle of the loch, but was moved to its shores during the 1930s when the level of the loch was raised for a hydro-electric scheme.