Roll up to Old Holborn
If you want to have an idea of what London looked like 500 years ago, you have to come here to Staple Inn in High Holborn. Built in 1586, as far as I know it is the only building of its type still survivng from before the Great Fire of London in 1666. Barring a small hiccup involving a flying bomb in WWII, it is still intact. History is here.