By the mid-1950s, a new generation of property owners had begun moving into the Heights, pioneering the "Brownstone Revival" by buying and renovating pre-Civil War period houses, which became part of the preservationist movement which culminated in the passage in 1965 of the Landmarks Preservation Law. In 1965, community groups which later became the Brooklyn Heights Association, succeeded in having the neighborhood designated the Brooklyn Heights Historic District by the New York City Landmarks Preservation Commission, the first such district in the city. This was followed in the following decades by the further gentrification of the neighborhood into a firmly middle-class area, which became "one of New York City's most pleasant and attractive neighborhoods."