the northern half of the lot. The elevators, as well as an auditorium and display area on the same floor, are within a black marble enclosure at the northwestern corner of the building. There is also a vehicular ramp to the basement garage, as well as a loading dock, from the western section of the 54th Street frontage, at the lot's northwestern corner. A white marble enclosure with stainless steel doors encloses an emergency exit stair at the southeastern corner of the ground floor. Above the ground floor, all facades contain a curtain wall with heat-absorbing glass panes as well as stainless steel. The curtain wall was fabricated and installed by General Bronze, which had then just completed the United Nations Secretariat Building curtain wall. Unlike at the Secretariat, where the narrower sides were faced in solid material, all sides of Lever House's slab are faced in glass. A small portion of the slab's western facade contains a service core with masonry cladding. Curtain wall The curtain wall contains vertical steel mullions that are anchored to the floor plates within the building. Between each set of mullions are glass window panes that cannot open. These consist of greenish panes for windows on each floor, as well as opaque bluish panels for spandrels between floors. The spandrel panels are separated from the window panes by horizontal mullions as well as muntin grilles. The spandrel panels were intended to conceal the masonry construction of the superstructure. The window panes are tall, with the sill being above the top of each floor slab, thereby concealing air-conditioning units beneath each window. The mullions are designed to be flush with the glass, projecting about from the outer surface of the glass panels. During nighttime, one of every five mullions is lit. Venetian blinds were used to reduce glare. During a renovation in the late 1990s and early 2000s, the curtain wall was moved forward by . The curtain wall was designed to reduce the cost of operating and maintaining the property and, as designed, was intended to filter out thirty percent of heat from sunlight. The fixed-pane windows were cheaper to install and reduced the amount of particulate matter that entered the building, as well as kept air conditioning costs down. Additionally, Unilever constructed a window-washing scaffold, which was suspended from a "power plant car" on the roof. The scaffold, designed by Kenneth M. Young