[mortov]

I also strongly recommend membership too. There is so much to see that a single visit will never be enough - time is complex and the astonishing story of measurement and ties to astronomy and navigation which were a coernerstone to allowing discovery and for our modern society to evolve are astonishing.

The time and navigation section at the Smithsonian in Washington is also an interesting adjunct but the true gem (to me) is Greenwich.

Plus, membership also gets free access to the Cutty Sark and the Queens House making for an interesting day or two in London for anyone to enjoy.