Trimontium was the largest Roman fort north of Hadrian's Wall, a 22-hectare complex at the foot of the Eildon Hills that served as a frontier base for nearly a century and a half. Excavations from 1905 onwards yielded one of the richest hauls of Roman material in Scotland, including the iron Newstead Helmet now in the National Museum of Scotland.
The site itself, a kilometre east at Newstead, is now just a grassed-over field with information boards, but the Trimontium Museum on the central square in Melrose tells the story properly, with replica armour, found objects, and a model of the fort at its height. Guided walks to the site run in summer.