In Greenwich, the Old Royal Naval College is opening up spaces usually off-limits to the public. Head to the Open House table in Lower Grand Square (the open-air courtyard between College Way and the Thames) to book in person, on the day. Highlights will include entry to Admiral’s House, from 11am to 5pm on September 13, where the Morning Room displays a collection of items relating to Lord Nelson. Walking tours of the Jacobean Undercroft, on September 12 and 13, will offer a rare chance to see inside the undercroft of the Queen Anne building which is the only remaining intact room from Greenwich Palace — the birthplace of Henry VIII, Mary I and Elizabeth I.