both presidential nominee Ronald Reagan and former President Gerald Ford stayed at the Renaissance Center. The "city within a city" concept was duplicated in the suburb of Southfield, when the Southfield Town Center office complex - with five inter-connected golden skyscrapers and an overall area of - was constructed from 1975 to 1989. In the ensuing years, the Renaissance Center would face competition from the growing suburban office market. In 1987, the elevated Detroit People Mover transit line began operation with a stop at the Renaissance Center. In 1996, General Motors purchased the complex and moved its world headquarters from what is now the historic Cadillac Place state office complex in the New Center district, to the Renaissance Center, in downtown Detroit. Meanwhile, Ford Motor Company maintained offices in one of the towers in the center. Before the acquisition, Sibley's Shoes had its headquarters in the center. Architects' initial design for the Renaissance Center focused on creating secure interior spaces, while its design later expanded and improved to connect with the exterior spaces and waterfront through a reconfigured interior, open glass entryways, and a winter garden. By 2004, GM completed an extensive $500 million renovation of the Renaissance Center. This included a $100 million makeover for the hotel. Among GM's first actions was to remove the concrete berms facing Jefferson Avenue. The renovation includes a lighted glass walkway which encircles the interior mezzanine for ease of navigation, while the addition of the winter garden provides riverfront access and a view of Canada. A covered skyway over Jefferson Avenue connects to the Millender Center, Courtyard by Marriott - Downtown Detroit, and Coleman A. Young Municipal Center. In July 2010, Blue Cross Blue Shield of Michigan announced plans to lease of Tower 500 and Tower 600 and relocate 3,000 of its employees from its building in Southfield, Michigan. In January 2015, General Motors announced its intent to renovate much of the complex to make it more inviting as a destination for visitors to Detroit. In 2018, the GM World showroom was renovated. The Renaissance Center is owned by General Motors. The hotel in the central tower is now managed by the Marriott hotel chain and is called the Detroit Marriott at the Renaissance Center. The 1,298-room hotel is one of the largest operated by Marriott. The rooftop restaurant (which previously had revolved) received a $10 million renovation and was operated by The