London's Smallest Public Sculptures (opens in new tab)

1) I think I can write my own encryption that would be better than every public module out there... no you can't

2) I think I can write my own scrolling logic in this website that works better than.... no you can't.

The John Snow Pump… where they sealed it up to stop Cholera is very small.

Also Novelty Automation (WC1R 4AX) is a tiny interactive museum/wharf end arcade which has some very intricate mechanical entertainments. Some are tiny.

The grave of Douglas Adams in the Highgate cemetery.