Ardenne Abbey

If you're traveling from Caen to Bayeux on your way to WWII sites, you may pass by a fairly new-looking church in the small village of Saint-Germain-la-Blanche-Herbe. Its aesthetic might seem old, sure, but its overall look is too new to be the original architecture. And after seeing so many beautiful old churches in France, it would be easy to pass by without giving it a second thought.
But to WWII historians as well as those who are on the search for WWII sites of interest in Normandy, this church – the Ardenne Abbey – is high on the list of places to pay one's respects to the fallen heroes of WWII. It was here that the Germans made their headquarters during the Normandy battles of June 1944, and it's the site of one of the most egregious violations of the Geneva Convention from the war.
In this sanctuary-turned-Nazi-base, 20 Canadian soldiers were executed by the German soldiers who had captured. Now, as horrific as that is on its own, it's understandable if it doesn't seem terribly out of the ordinary; thousands of soldiers lost their lives in the Normandy battles. But the fact that they were either shot or beaten in the backs of their heads is what ultimately resulted in the trial of Brigadeführer Kurt Meyer, commander of the 25th Panzer Grenadier Regiment, and the resulting verdict of guilty under the Geneva Convention. 
Because the Ardenne Abbey was soon lost to Allied bombardment, it has since been reconstructed; thus its new-looking exterior. And on the grounds visitors will find a memorial to the executed soldiers, with the solemn vow, “Lest we forget.”
While so many of the WWII museums in Normandy focus on the victories, this humble memorial serves as a haunting reminder that even here, so far from the atrocities to the east, had known its own kind of brutality. Lest we forget.