Starting in the 1950s, a total of 464 tower blocks above six storeys were built in Birmingham, 7% of all the tower blocks constructed in the United Kingdom, with the first Birmingham tower blocks being built in Duddeston, part of the Nechells and Duddeston Redevelopment Area, in the late-1950s. They were designed by S.N. Cooke and Partners and proved to be extremely costly for the city council. In 1960, the Lyndhurst estate in Erdington was completed and the entire estate won a Civic Trust award in 1961. The main tower block on the estate, the 16 storey Harlech Tower, became the tallest tower block in the city, although it was later surpassed by many more tower blocks including the 32 storey Sentinels in the city centre, which were inspired by the Marina City complex in Chicago. Stephenson Tower was another city-centre tower block, located on top of New Street station, although the refurbishment of New Street station saw the demolition of the tower. A group of four tower blocks located behind The Rep Theatre on Broad Street have also undergone an extensive renovation to improve their insulation and appearance.