General Post Office, London

The General Post Office in St. Martin's Le Grand (later known as GPO East) was the main post office for London between 1829 and 1910, the headquarters of the General Post Office of the United Kingdom of Great Britain and Ireland, and England's first purpose-built post office.

Originally known as the General Letter Office, the headquarters of the General Post Office (GPO) had been based in the City of London since the first half of the 17th century. For 150 years, it was in Lombard Street, before a new purpose-built headquarters, designed by Robert Smirke, was opened on the eastern side of St. Martin's Le Grand in 1829. As well as functioning as a post office and sorting office, the building contained the main offices and facilities for the Postmaster General of the United Kingdom and other senior administrative officials.

While externally attractive, Smirke's General Post Office suffered over the years from internal shortcomings due to ever-increasing demands on available space. In the later part of the 19th century the GPO expanded into other buildings on St Martin's Le Grand, and further afield. After a new building was opened in nearby King Edward Street, Smirke's General Post Office was demolished in 1912.

The headquarters staff had already moved, in 1874, into new premises (GPO West) just across the road from Smirke's building. Twenty years later they moved into another new building on St Martin's Le Grand (GPO North), which continued to serve as Post Office Headquarters until 1984.