Simpsons of Piccadilly was a large retail store situated at 203–206 Piccadilly in central London, England. It was created by Alexander Simpson and the architect Joseph Emberton. When it opened in April 1936, it was the largest menswear store in Britain, and is now a Grade I listed building due to its innovative construction. Its original purpose was to house the entire range of clothing provided by the tailoring company S. Simpsons and DAKS. It was later purchased by the Waterstones chain of bookshops.