Alton Side House and Cottage Adjoining

Alton Side House and the adjoining cottage are a pair of bastle houses dating from the 16th century, with alterations made in the 18th and 20th centuries. They are constructed of rubble with large, roughly-shaped quoins and feature a slate roof, along with a squared stone stack on the right gable. The left gable stack has been rebuilt in brick on its original base.

The front elevation displays the remains of an original ground floor door to the right of a 19th-century boarded door, while other openings date from the 18th and 20th centuries. The rear elevation includes a blocked first-floor door to the eastern bastle, which is square-headed with a moulded surround, and a blocked single-light window in a chamfered surround. The wall of the western bastle is set slightly forward, and there are 20th-century windows present. There is also a range of former farm buildings adjoining the western bastle, which are not of interest.

Despite the alterations, the bastles retain several original features, most notably the blocked first-floor door, which has an unusual character that is almost reminiscent of Scottish architecture.