National Maritime Museum London
The National Maritime Museum is really three museums in one, all standing in the beautiful grounds of the Royal Park at Greenwich. The Maritime Museum and Queen's House and stand near the river Thames. Overlooking those buildings - and all of London - is the Old Royal Observatory. The Maritime Museum is the largest of its kind in the world and will quickly immerse you in all things naval. 16 galleries present information on everything from marine plants, to piracy and slave trading.
You can take the helm of a variety of ships and see dozens of sea-going vessels. At the Royal Observatory visitors can stand in both the eastern and western hemispheres simultaneously by placing their feet either side of the Prime Meridian - the center of world time and space. This is the spot where global navigation was first tamed, where longitude and latitude where determined and where the world sets its watch to this very day. Daily planetarium showings teach the importance of the heavens to our daily existence in ways that you may not even be aware of. Admission to the facility is free.