One Rathbone Square is a commercial building in London, and was the UK headquarters of Facebook.

The site was bought from Royal Mail Group for £120m in September 2011; it was the former West End Delivery Office.

It is situated off Oxford Street, in the east of the City of Westminster, and is on the boundary with the London Borough of Camden.

The site costs Facebook £17.8m per year to rent, with a fifteen-year term on the contract.

[2] It features a build called LDN_LAB, a business incubator for tech startup companies.