Memorial de Caen This has got to be one of the best museums about anything, anywhere in the world: huge, comprehensive and profoundly moving. Served by a dedicated bus route, and only a few miles from the centre of Caen it provides an overview of the ravages of war in the 20th Century, and has a large parkland garden dedicated to the Canadian Forces who fought in the Normandy Campaign.
They also offer a half-day guided minibus tour to some of the important invasion sites, in several languages. I took this, and can highly recommend it; you will see more places in a morning or an afternoon than you could reach in 2 whole days by bus.
The imposing frontage of the museum leads you into a foyer where the visitor comes into the gunsights of a heavily-armed Typhoon aircraft, suspended from the ceiling as if in a low attack flight; quite a sobering perspective….
Prepare to be informed and deeply moved; the museum covers the whole military theatre, and has a huge amount of material (including films and audio booths) relating to the civilian casualties of war. The final section of the building covers post-WW2 developments, Korea, Vietnam, the Cold War and the Fall of the Berlin Wall (of which they have some sections on display). The museum has a good restaurant, toilets, shop and an extensive reference library, and I feel it is an essential visit on any itinerary: allow at least 3 hours to get an idea of what is there, and a full day to really take it all in.