Flats can represent a small or large investment, with studio flats at the bottom of the scale and entire apartment blocks at the top. Flats may be purpose built, with some twentieth century blocks becoming landmarks in their own right. Larger houses in urban areas are often converted into several flats to meet the changing needs of modern households. Buying to let can be a good source of income, with no shortage of tenants, especially in cities. Buying a flat as a home, too, can represent a good investment for the future.