The new Caltrans District 7 Headquarters covers an entire city block downtown Los Angeles, directly opposite City Hall. It serves the California Department of Transportation (Caltrans) and the Los Angeles Department of Transportation. Built on a $165,000,000 budget it opened in September 24th 2004. Its futuristic and environmentally-friendly design has won its designer Thom Mayne the 2005 Pritzker Prize. Enrobed in a constantly changing mechanical skin that is alternately open or closed depending on the conditions of outside temperature and sunlight, the building's fundamental property is that of transformation. At dusk the building is transparent, textured and windowed, while at mid-day it is buttoned up against the sun, appearing to be devoid of windows entirely. The building's south facade is entirely surfaced with photovoltaic cells that will generate approximately 5% of the building's energy while shielding the facade from direct sunlight during peak summer hours. The facade along Main Street features an innovative double skin of glass behind perforated aluminum panels. The panels open and close mechanically timed with the movement of the sun and weather conditions. Marking the entrance of the building at 100 South Main Street is a super-graphic, forward-canted sign towering 40 feet over the sidewalk.