One of the Royal Parks. You could lose yourself wandering around Greenwich anyway where, in addition to pay-to-visit attractions like the Cutty Sark, there are free places like the Queen’s House and the National Maritime Museum to see. Greenwich Park, once part of the grounds of Greenwich Palace (birthplace of Henry VIII and Elizabeth I), overlooks the Thames and is packed with things of interest. There’s a deer park, orchard – and it is home to the Royal Observatory, Greenwich Mean Time and the Prime Meridian (which you need to pay to visit). Less well known is Elizabeth’s oak, alleged scene of Tudor picnics and what-not, and a Saxon cemetery.
Post code is approximate