49 Belgrave Square is a Grade II* listed house in Belgrave Square, Belgravia, London. It was finished in 1851, designed by Thomas Cubitt. In 1859, Mayhew & Knight built the entrance and added the octagonal lobby. It was originally known as the "Independent North Mansion" The first owner, Sidney Herbert, 1st Baron Herbert of Lea, named it "Belgrave Villa". His son, Sidney Herbert, 14th Earl of Pembroke was born there in 1853.
After Herbert, the Duke of Richmond lived there. The house was subsequently acquired by Alfred Beit, and his brother Sir Otto Beit inherited it in 1906. His son Sir Alfred Beit, 2nd Baronet grew up there and on his father's death in 1930 inherited the house, together with his large art collection. He relocated to Kensington Palace Gardens, and sold the house in 1936.
The building was acquired by Argentina in 1936, and has since been used as their Ambassador's official London residence. It has been opened to the public one weekend a year since 2006, as part of Open House London, which notes the "sumptuous interiors still intact". In World War II, the house became a meeting place and haven for Argentines who volunteered in the British forces, mostly as pilots.