The regeneration of the city during the 1990s and 2000s also saw many residential areas of the city substantially altered. A notable example was the Pype Hayes council estate in the Erdington area of the city, which was built in the interwar years but was eventually completely redeveloped due to structural defects. Many of the city's 1960s council properties, mostly multi-storey flats and maisonettes, have also been demolished in similar redevelopments, including the large Castle Vale estate in the north-east of the city, where all but two of the estate's 34 tower blocks were demolished as part of the regeneration of an estate which had been blighted by crime, unemployment and poor housing.