Detailed Instructions: In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.
Problem:Article: From the modern London Eye to the historic Tower of London, below are London's most visited tourist attractions. Many of London's top attractions are free, making them affordable places to learn about some culture. Whether you prefer history or modern art, you'll find it at one of these must-visit spots. British Museum The world-famous British Museum exhibits the works of man from prehistoric to modern times, from around the world. The most interesting and exciting parts include the Rosetta Stone, the Parthenon sculptures and the mummies in the Ancient Egypt collection. Some exhibitions require tickets. National Gallery The greatest and most beautiful building of Trafalgar Square, London's National Gallery is a vast space filled with Western European paintings from the 13thto the 19thcenturies. In this impressive art gallery you can find works by masters such as Van Gogh, da Vinci, Botticelli, Constable, Renoir, Titian and Stubbs. Some exhibitions require tickets. Tate Modern Sitting on the banks of the Thames is the Tate Modern, Britain's national museum of modern and contemporary art. Its unique shape is due to it being a power station before. The gallery's restaurants offer wonderful views across the city. Some exhibitions require tickets. Coca-Cola London Eye The Coca-Cola London Eye is a major feature of London's skyline. It has some of London's best views from its 32 capsules, each weighing 10 tonnes and holding up to 25 people. Climb aboard for a breathtaking experience, with an unforgettable view of more than 55 of London's most famous landmarks -- all in just 30 minutes! Madame Tussauds At Madame Tussauds, you'll come face-to-face with some of the world's most famous faces. From Shakespeare to Lady Gaga you'll meet influential figures from show business, sport, politics and even royalty. Strike a pose with Usain Bolt, get close to One Direction or receive a once-in-a-lifetime audience with Her Majesty the Queen. 
 Answer: Both have chargeable exhibitions.
Solution:
What do the British Museum and the National Gallery have in common?