This is taken from my review about the Museum
If you're into Military History from the Middle ages to the present, then the Royal Military History Museum in Brussels is a must. First of all the price is right, it's free. The first room displays the Belgiun military in the 19th Centruy. A nice warm up to the rest of the museum. More rooms are form the middle ages up to the 19th centruy. Then we walked into the WW 2 exibit. There are 3 floors dedicated to World War 2. Lots of uniforms, artifacts, and stuff on display from that great war. The World War one exhibit is a good on also. Just one floor this time but still has many weapons, Uniforms, shells, and tanks from the First World War.
Then we walked into the Airplane Hanger. This room alone is a must for anybody into flying or military history. This is a huge hanger with many military aircraft from Balloons to the F-16. It has a mig, an F-4, and World War 1 fighter planes. Also in the hanger is a café where you can get a beer or something else to drink. This is not free of course but it’s a nice midway point to rest. We spent a long time in the hanger but we yet had to check out the very impressive tank exhibit. First the indoor part of the exhibit was just scale models of tanks. That’s ok but I was anxious to get outside and see the actual tanks. I was not disappointed when we got outside. More then 30 tanks are on display outside here from the British, French, Russian and the Americans. In my opinion the Aircraft and the tanks were the best part, but we still had the Navy section and the Napoleonic era to cover. It is a good day trip for anybody interested this sort of thing. We spent 3 or 4 hours in there all together and living in Belgium, that makes a great thing to for a day trip.