(For the recruitment agency, see Brook Street Bureau plc.) Brook Street is one of the principal streets on the Grosvenor Estate in the exclusive central London district of Mayfair. Named after the Tyburn Brook that formerly ran nearby, it was developed in the first half of the 18th century and runs from Hanover Square to Grosvenor Square. The continuation from Grosvenor Square to Park Lane is called Upper Brook Street. Both sections originally consisted of typical London terraced houses, mostly built to individual designs. Some of them are quite grand and were designed by well known architects for aristocratic clients, especially near Grosvenor Square, while others are more modest. Some of the original houses survive while others have been replaced by buildings from a variety of periods.