The London home of the British monarch is more impressive from the front, viewed across the gold-tipped fences and the Victoria Memorial roundabout, than at close quarters — Buckingham Palace's facade was redesigned in plain Portland stone in 1913 and is deliberately reserved. The Royal Standard above the building tells you when the monarch is in residence.
The Changing of the Guard takes place outside on the forecourt at 11am several days a week (currently Monday, Wednesday, Friday and Sunday from May to July, less often in winter — check the official site as the schedule shifts). Arrive at least 45 minutes early in summer to see anything. A quieter alternative is to watch the Horse Guards Parade dismounted at 4pm daily on Whitehall.
For ten weeks in late summer the State Rooms open to the public — the Throne Room, the Ballroom, the picture gallery — for ticketed visits. Book well ahead. The rest of the year you make do with the Royal Mews around the corner, where the gilded state coaches and the working stables can be visited year-round.