The Protestant church of Boazum or Saint Martin’s church is a late 12th century Romanesque church with inner walls of brick and outer walls of tuffstone with a 13th-century tower. It was built out of yellow and red brick. The choir is likely the oldest part of the building. The church was originally a Roman Catholic temple dedicated to Saint Martin, becoming a Protestant church after the Protestant Reformation.
References:The historical centre of Briançon is a strongly fortified town, built by Vauban to defend the region from Austrians in the 17th century. Its streets are very steep and narrow, though picturesque. Briançon lies at the foot of the descent from the Col de Montgenèvre, giving access to Turin, so a great number of other fortifications have been constructed on the surrounding heights, especially towards the east.
The Savoyards made two raids into French territory in 1691 and 1692. As a result, Vauban was dispatched to inspect the frontier defences, which had been ill-equiped to deal with the attack from Savoy. He returned to the area in 1700 to check on the progress that had been made since his first visit. When Vauban visited Briançon, work on the defences had already started under a local engineer, Monsieur d"Angrogne in 1692.