What is no10?

No10 typically refers to 10 Downing Street, the official residence and office of the Prime Minister of the United Kingdom. It is located in the City of Westminster in London and has been the official residence of the Prime Minister since 1735. The building is over 300 years old and has undergone significant renovations and additions over the years. It is situated near various other government buildings and landmarks, such as the Houses of Parliament and Buckingham Palace. The office is heavily guarded and access is restricted to authorized personnel only.