St Martin's church is a 'very remarkable building with windows glowing with gemstone colours' according to architectural historian Nikolaus Pevsner.
In the late 1st century AD the Romans built a series of forts stretching from east to west between the Tyne and the Solway, joined by a road known as Stanegate. The forts predated Hadrian's Wall and one was erected above the River Irthing.
After the Romans withdrew a community grew up to the southwest. Local tradition says that in the late 4th century St Ninian built a church and holy well within the earthwork walls of the old Roman fort. Ninian dedicated his church and holy well to his teacher, St Martin of Tours.
Some 800 years later a stone church was erected on the site of Ninian's church, beside the northeast ramparts of the Roman fort. This second church, like the first, was dedicated to St Martin, and served as the parish church for the growing settlement of Brampton. Stones to build the church were robbed from Hadrian's Wall.
The first documentary evidence of Brampton Old Church comes in AD 1179 when it is mentioned as a gift to Lanercost Priory. During the 14th century a fortified tower was added to the west end of the church to protect it from raids during the Border Wars. The settlement was forced to move from its place beside the River Irthing when the local lord wanted to enclose the area to create a deer park, but the inhabitants continued to worship in the Old Church for over 600 years.
The church was finally declared redundant in 1978 and all the internal furnishings were taken away. It now stands alone within the ramparts of the Roman fort, with only a farmhouse for company.