Tucked away in the southern Spanish port city of Cartagena is a very nice little military museum, majoring on the Artillery arm of the Spanish Armed Forces, which I recently toured – and I've created a YouTube video of the most interesting stuff there, which is online at youtu.be/d4yOlpL7MFQ
The museum has an extensive collection of field guns, ranging from the 1800's up to the present day, displays on ammunition, sights and ranging devices, small arms, uniforms, as well as several historical dioramas and maps showing the growth and defences of the Cartagena naval bse through the ages.
The left-field highlight (for some) though is a collection of model tanks and fighting vehicles (every one representing a different model, marque or variant), all in what looks like 1/72nd scale, which were built by one man and which do/did hold the Guiness Book of Records title for being the largest collection of military models in the world.
The official website of the museum is here: ejercito.defensa.gob.es/unidades/Madrid/ihycm/Museos/cartagena.html
There's also a lot of great Roman, Medieval and Carthaginian stuff in Cartagena too for the history buff.