In 2001, atop Chicago City Hall, the roof gardens were completed, serving as a pilot project to assess the impact green roofs would have on the heat island effect in urban areas, rainwater runoff, and the effectiveness of differing types of green roofs and plant species for Chicago's climate. Although the rooftop is not normally accessible to the public, it is visually accessible from 33 taller buildings in the area. The garden consists of 20,000 plants of more than 150 species, including shrubs, vines and two trees. The green roof design team was headed by the Chicago area firm Conservation Design Forum in conjunction with noted "green" architect William McDonough. With an abundance of flowering plants on the rooftop, beekeepers harvest approximately of honey each year from hives installed on the rooftop. Tours of the green roof are by special arrangement only. Chicago City Hall Green Roof won merit design award of the American Society of Landscape Architecture (ASLA) competition in 2002.