Whether you're a first-timer in London — or a long time Londoner who's fallen by the wayside — you've got to tick these London attractions off your list.
The Old Royal Naval College
The Old Royal Naval College is built on the site of the former Greenwich Palace, where Henry VIII, Elizabeth I and Mary I held their courts. Take in the visitor centre, National Maritime Museum, Painted Hall (where Nelson's body was laid in state) and Queen's House (all free). Consider forking out extra for the Cutty Sark (see further below). We've also found a few less visited nooks you should seek out.
Fun fact: Many Hollywood blockbusters have been filmed here, including parts of Pirates of the Caribbean, and a fair chunk of the 2012 musical Les Misérables.
The Royal Observatory
Behind the Old Royal Naval College, and across Greenwich Park, lies the Royal Observatory. Explore time and longitude, with various ingenious timepieces crafted through the ages, and don't forget to straddle the Meridian Line. If you want to watch a show in the Planetarium, book ahead.
Lunchtime concerts, weekend family fun, literary festivals and ground-breaking exhibitions: just another day in the life of Southbank Centre. Peruse the programme to see what's on when you're in town. Look out for blockbusters such as Carsten Höller's zany slide, back in 2015. Or just admire the brutalist architecture.
Find out more: Things You Might Not Have Done On South Bank
This former Bankside Power Station is now a powerhouse of modern art. Wander through the free collections, boasting Francis Bacon triptychs and Marcel Duchamp urinals. Or fork out a bit of money to visit the Herzog & de Meuron's extension, The Switch House. Few modern art galleries in the country can compete with this behemoth.
St Paul's Cathedral
A stroll across the Millennium Bridge whisks you back centuries to Wren's finest moment, St Paul's Cathedral. Introductory talks and guided tours are included in the (rather steep) ticket price. Take a friend along, to make the most out of the Whispering Gallery. Book ahead for a guaranteed visit and fast track entry.
Learn more: The Secret Rooms Of St Paul's Cathedral
Get geeky on Exhibition Road, at three of London's biggest museums. See Williams Morris prints, towering Michelangelo plaster casts and blockbuster exhibitions (think David Bowie Is) at the V&A. Come face to face with dinosaurs and blue whales at the Natural History Museum (or ice skate out the front at Christmas). Marvel at Charles Babbage's Victorian computer, and play around at Wonderlab in the Science Museum. There's weeks worth of informative fun to be had — a lot of it for free.
The Tower of London
Entrance to the Tower of London isn't exactly cheap; then again, how many attractions give you a thousand years worth of history? Let the legendary Beefeaters guide you around this palimpsest of a palace/fortress. Tell them you know that the 'legend of the ravens' only dates back to the 1940s.
Fun fact: The Kray Twins were among the last people to be imprisoned in the Tower of London in 1952, for failing to report for National Service.
Be wooed by the cobbled courtyard of Somerset House, then sign up for a guided tour. Otherwise, peruse its Courtauld Gallery, brimming with impressionist and post-impressionist works. In the summer, there are outdoor film screenings. In the winter months, there's an ice rink. A constantly changing, but perennial London landmark.
Learn more: 7 Secrets of Somerset House
The Houses of Parliament
Home of British politics, the Houses of Parliament — or the Palace of Westminster if you will — is very much functioning. But just because the politicians are going about their business, doesn't mean you can't have a snoop. Guided tours and audio tours are on offer — one of them followed by a Thames-side cream tea. If you want to get up Big Ben, you'll need to write to your MP for permission way in advance.
The National Gallery
The National Gallery has over 2,300 works — dating from the 13th century through to the 20th century — from Da Vinci and Raphael to Monet and Van Gogh. One of London's roomiest exhibitions spaces, they could fit almost as many double-decker buses in here as they've got paintings. The National Portrait Gallery next door makes for a worthy add-on. Both permanent collections are free.
Fun fact: It also has a secret room, which is also the gallery's biggest room, only occasionally open to the public.
Admire the Victoria Memorial. Hang around for Changing the Guard. Impress fellow tourists with your knowledge that the Union Flag only flies when Her Maj is out. Of course, standing outside the palace gates is one thing: if you want to go inside, book a tour for August or September.
Top tip: Changing the Guard takes place every day from April-end of July, but only on alternate days the rest of the year. Inclement weather might see it cancelled.
Learn more: 13 Secrets of Buckingham Palace