Edinburgh Castle

In front of you is the rock that explains the whole of Edinburgh. Castle Rock is the plug of a volcano that went extinct some 350 million years ago: ice scoured it on three sides and left a tail of land running east, the very ridge you're standing on and down which the Royal Mile runs. People have lived on this summit since the Bronze Age.

1Nine centuries of sieges

The city's oldest building is up there: St Margaret's Chapel, built in the 12th century by King David I in memory of his mother. The rest of the castle changed with every war. The curved wall you can see, the Half Moon Battery, went up after the 'Lang Siege' of 1571–1573, when supporters of Mary Queen of Scots held out here until English artillery brought down David's Tower.

Inside are the Honours of Scotland – crown, sceptre and sword – the oldest crown jewels in the British Isles. They spent over a century locked in a chest until a team that included Walter Scott brought them back to light in 1818. You'll also find Mons Meg, a giant cannon from 1449.

If you hear a bang at one o'clock sharp, don't panic: it's the One O'Clock Gun, fired since 1861 so that ships could set their clocks.

2What to look out for

• The gatehouse statues: William Wallace and Robert the Bruce, the two heroes of the Wars of Independence, put in place in 1929.
• The Half Moon Battery, the great curved wall on the rock.
• The Witches' Well, a small bronze fountain of 1894 set against a wall at the eastern end of the Esplanade, recalling the women executed for witchcraft on Castlehill.