You must have a valid passport to enter the UK. It should be valid for the whole of your stay. You may also need a visa, depending on which country you're from. Check if you need a visa to come to the UK.
People Also Ask
Citizens Need A Visa To Travel To The UK. According to the UK government, the United States is among the visa-waiver nations. Therefore, as a U.S. citizen, you can enter the territory of the United Kingdom for a period of up to 6 (six) months with no need to apply for a visa.
Depending on the length and purpose of their trip, US citizens may be able to visit the UK visa-free. For short terms of up to 6 months, there is no need for American visitors to request a visa. Even with the introduction of the ETA, US travellers will not need to apply for a visa.
American Visa UK: What can you do? Because Americans are known as non-visa nationals in the UK, to answer the question do American citizens need a visa for UK? They don't. American citizens are able to visit for up to six months without a visa.