Stand on the north bank of the Thames at Westminster and you can take in the Elizabeth Tower, the river, and the London Eye in a single sweep of your head. That compression is what makes London work for a short trip: the big set pieces sit within walking distance of each other, and the transport underneath them is the world's oldest rapid transit system.
The city suits travellers who are happy to walk between clusters of sights and use the Underground for the longer hops. It also suits anyone travelling on a budget, since the majority of the major museums have no general admission charge, though special or temporary exhibitions usually attract an admission charge.
This guide covers the landmarks, museums and galleries, and parks that are worth building a day around, with practical notes on timing and what to combine with what.
Top things to do in London
1. Tower of London
Situated just south east of the City, this is London's original royal fortress by the Thames. It is over 900 years old, contains the Crown Jewels, is guarded by Beefeaters, and is a World Heritage site. It is also considered by many to be the most haunted building in the world, and guided ghost walks of the building sometimes run.
You can even have a good meal in one of the buildings on the property. The Tube stop is Tower Hill, which puts Tower Bridge within easy reach on the same outing.
2. Westminster Abbey and the Palace of Westminster
The seat of the United Kingdom parliament and a World Heritage site, and the setting for royal coronations since 1066. The Elizabeth Tower, the clock tower commonly known by the name of its bell, Big Ben, and the Houses of Parliament form the wider complex in Westminster.
The Palace of Westminster is open to the public only for viewing parliamentary debates, and tours of the building are available in July and August when Parliament is away on summer recess. Westminster Abbey also has a restaurant and a café that both serve good food. Tube: Westminster.
3. Buckingham Palace
The London residence of the King, in Westminster. It is open for tours during the summer months only, but it is worth the walk past even if you do not go in. Tube: Green Park.
The Changing of the Guard spans three locations, Buckingham Palace, St James's Palace and Wellington Barracks, and usually begins at 10:43. Check the published dates before you plan a morning around it.
4. British Museum
A treasure trove of world cultures from across the ages, on par with the Paris Louvre and New York's Metropolitan Museum. Entry is free, as it is at the majority of London's museums, which makes it easy to visit more than once. Tube: Holborn.
5. St Paul's Cathedral
Sir Christopher Wren's great accomplishment, built after the 1666 Great Fire of London, with the great dome still seated in majesty over the City. A section of the dome has such good acoustics that it forms a "Whispering Gallery".
There is also a viewing area that offers views of the surrounding area, including the Millennium Bridge that lies nearby. Tube: St Paul's.
6. Tower Bridge
The iconic 19th century bridge located by the Tower of London near the City, decorated with high towers featuring a drawbridge. The public are allowed access to the interior of the bridge via the Tower Bridge Exhibition, with tickets purchasable online or at the bridge. Tube: Tower Hill.
7. London Eye
The world's fourth-largest observation wheel, on the South Bank of the Thames, with magnificent views over London. Pair it with a walk along the South Bank. Tube: Waterloo.
8. Tate Modern
One of the major galleries with no general admission charge, so you can drop in without committing a whole afternoon. Tube: Southwark or Blackfriars.
9. Tate Britain
Also free to enter, and a natural pairing with a Westminster or Pimlico day rather than with its South Bank namesake. Tube: Pimlico.
10. Natural History Museum
Another of the free-entry museums, in South Kensington, where several of the major collections sit close together. Tube: South Kensington.
11. London Transport Museum
A notable smaller museum covering the city's transport history, in Covent Garden, which makes it easy to fold into a shopping or theatre evening. Tube: Covent Garden.
12. Royal Observatory Greenwich
Part of the Royal Museums Greenwich group, reached via the DLR at Cutty Sark. Build the trip around the whole cluster rather than a single building.
13. Cutty Sark
The ship is the other anchor of the Greenwich cluster, and the DLR station is named after it. Combine it with the Royal Observatory on the same visit.
14. View from the Shard
The Shard is a futuristic triangular skyscraper in South Bank that dominates the London skyline and is the tallest building in the UK. There is a viewing deck on the 72nd floor that is open to the public, and tickets must be booked via the website. Tube: London Bridge.
15. Hyde Park and Kensington Gardens
These adjoining spaces make up a huge open space in central London and are very popular for picnics. Within Kensington Gardens, the Diana, Princess of Wales, Memorial Playground is a free playground for young children featuring a huge wood pirate ship. Tube: High Street Kensington, Marble Arch, Green Park or Hyde Park Corner.
If you only have one day
Morning. Start at Westminster Abbey and the Palace of Westminster, timing your arrival so you can see the Elizabeth Tower and the Houses of Parliament before moving on. Walk through St James's Park towards Buckingham Palace, and check the published dates if you want to catch the Changing of the Guard, which usually begins at 10:43 and spans Buckingham Palace, St James's Palace and Wellington Barracks.
Afternoon. Cross to the South Bank and ride the London Eye for views over the city. Then take the Tube to Tower Hill for the Tower of London, and walk over Tower Bridge while you are there, since the two sit together.
Evening. Head to South Bank for the View from the Shard, booking your ticket via the website in advance. If you would rather stay at ground level, finish at the Tate Modern instead.
Frequently asked questions
Do I need to book London attractions in advance?
For some, yes. Tickets for the View from the Shard must be booked via the website, and Tower Bridge Exhibition tickets can be purchased online or at the bridge. Buckingham Palace is open for tours during the summer months only.
Which museums are free to enter?
The majority of London's museums have no entrance charge, including the British Museum, Tate Modern, Tate Britain and the Natural History Museum. Special or temporary exhibitions usually attract an admission charge.
When can I tour the Palace of Westminster?
The Palace of Westminster is open to the public only for viewing parliamentary debates. Tours of the building are available in July and August when Parliament is away on summer recess.
How do I get around between these sights?
The London Underground, the world's oldest rapid transit system, connects the clusters. Each listing above names its nearest Tube or DLR station so you can plan the hops between them.
Pick the two or three sights that matter most to you, check the booking requirements, and start shaping your days around them.