Portland Place was created in 1773 as a speculation by two of the leading architects of the time, Robert and James Adam.
It was originally designed as a series of private palaces, though the speculators quickly acknowledged this was a little ambitious. The current terrace, of which number 21 is the centerpiece, began in approximately 1776 and was completed around 1778.
Today, 21 Portland Place is a Grade II* listed building, and contains some of the original features which are typical of the Adam style. Rooms are available for meetings, events, exhibitions and filming locations