The top of the Royal Mile is the famous half; this is the other one. Below the World's End, the Canongate runs wider and calmer down to the foot of the Old Town, where three very different monuments sit almost on top of each other — a 17th-century kirk, a 21st-century parliament, and the raw green wall of Arthur's Seat behind both. The walk is about that collision of centuries.
Start at the Canongate Tolbooth, its clock thrust out over the street, and drop to Canongate Kirk — Dutch-gabled, gilded stag over the door, Adam Smith in the yard. Then the foot of the Mile and Enric Miralles' Parliament, opened in 2004 and argued over ever since: concrete and oak folded into the shapes of upturned boats. Wander the public concourse. The white tents of Dynamic Earth sit under Salisbury Crags just south.
It ends at Holyroodhouse, the King's palace, with the ruined abbey beside it and Arthur's Seat rising straight behind. Stand at the park gate. You don't have to climb it — but you'll want to come back and do it.