The Metropolitan line is one of the major lines of the London Underground, serving the city of London and its surrounding areas. It is known for being one of the oldest underground railway lines, first opening in 1863. The line runs from Aldgate in central London to Amersham and Chesham in Buckinghamshire, covering a distance of approximately 40 miles. The Metropolitan line is notable for its unique mix of urban and suburban services, connecting key areas such as Baker Street, Harrow-on-the-Hill, and Watford. It operates both underground and above ground, providing passengers with a diverse travel experience across different landscapes.