In the Charente countryside, down 2km of winding lane from the rather nondescript town of Blanzac-Porcheresse (south-east of Angoulême), a small chapel stands beside a farmhouse. Although it’s not hard to find, it takes a little effort to get there.

This is the Chapelle des Templiers, built around 1160. It may look like an ordinary church from the outside, but inside it contains extraordinary wall paintings commissioned by the Knights Templar, an order of warrior-monks who, at the height of their powers, were cast into disgrace by the king of France. Their leaders were burned at the stake and their properties dispersed, leaving behind few facts and many conspiracy theories.

There are few authentic Templar places left in their homeland, France – it’s almost as if every trace of them has been wiped out, but this chapel somehow survived. Ruined during the hundred years war, the chapel was used as a barn until someone realised that its walls were decorated with murals showing the knights fighting in the Crusades.

A restored mural at the chapel

By 2013, the paintings were in a serious state of deterioration but a two-year programme of restoration has just been completed and the result is a bit like looking at a pristine Bayeux tapestry through a filter, or a projection of a medieval newsreel. The paintings are all in tones of red and orange. One scene shows the Frankish knights in battledress riding into action from a walled city that may be Antioch. Next to the window, there is a ship on a rough sea.

The restoration process has left the chapel feeling more modern than medieval in atmosphere but this is still as close to seeing the real Templars as you’re ever going to get. In summer, the chapel gets a few tourists, but off-season, when you have to summon the key holder to open it for you, you may well get the place to yourself.

• Open Jul–Aug, Tue–Sat, 3.30pm–5.30pm. At other times, call +33 5 45 64 0731 or contact the tourist office in Blanzac-Porcheress, sudcharentetourisme.fr

Nick Inman is the author of A Guide to Mystical France: Secrets, Mysteries, Sacred Sites, published by Findhorn Press. To order a copy for £14.99 including UK p&p visit theguardianbookshop or call on 0330 333 6846