Also commissioned were eight banners by Alexander Calder. The banners, ranging from to , were hung from the atrium ceiling and had colorful sun, flower, moon and night designs. The dyed cotton and silk banners, the only banners Calder ever designed, were removed during the renovations in the 1980s and were subsequently lost. After pressure from the Philadelphia Redevelopment Authority art program to search for the banners, they were discovered in a storeroom in the early 2000s. In 2009 some of the banners were put on temporary display at the Free Library of Philadelphia while the Redevelopment Authority works to find a place to have them displayed permanently. Wolgin said his goal in commissioning the three pieces of art was "to provide art that would enhance Philadelphia by integrating into the daily life of those who live or work in the city the joy and inspiration derived from great art". Former head of the Redevelopment Authority art program Mary Kilroy said the art installed at Centre Square was the point when Philadelphia began to build its reputation as a great promoter of public art. In association with the Mural Arts Program, CommonWealth REIT is installing a glass mosaic mural below the "Clothespin" at the underground entrance to Centre Square. Made by Miriam Singer and Emilie Ledieu, the mural is intended to represent the geographies of the people who pass through the plaza and is expected to be completed in November 2011. The complex's largest tenant is the management consulting firm Towers Watson. Predecessor Towers Perrin had offices in Centre Square since 1975 and after its lease renewal in 2004 occupies between and square feet in the east tower. Saul Ewing leases on the 36th, 37th, and 38th floors of Centre Square II. The law firm has made the building its headquarters since shortly after the building opened. Cable company Comcast made the Centre its headquarters from 1991 to 2007. Comcast moved into the complex after a fire seriously damaged its former headquarters at One Meridian Plaza across the street. It left Centre Square for its new headquarters in the Comcast Center despite attempts by HRPT Properties Trust to convince them to stay. In 1999, Lincoln National Corporation moved from Fort Wayne, Indiana to Centre Square. The company makes  in the west tower its headquarters despite moving 400 employees, including its top management, outside of Philadelphia and into Radnor Township, Pennsylvania in 2007. Law firm Conrad O’Brien also leases space in the west tower. It leased on the 39th and 40th floors in 2011. A restaurant called Top of Centre Square was located in Centre Square II.