deck storage space to accommodate the sculpture while still being able to navigate the Saint Lawrence Seaway. As part of the shipment, four miniature scale models of the sculpture were included to aid with customs clearance. The sculpture was delivered to the Detroit City-County Building and installed onto the marble base for the September 23, 1958 dedication ceremony. The Marshall M. Fredericks Sculpture Museum has the original plaster head for The Spirit of Detroit, as well as a quarter-scale plaster model. The sculpture has regular maintenance, as well as restorations. Once a year, the sculpture is cleaned with non-ionic, biogradable detergents and customized petroleum-based waxes are used for protection. The annual maintenance also includes applying heat to the bronze surface and cupric nitrate in order to preserve the green color and patina. In 1984, the sculpture was covered in plastic while the marble panels behind the statue were replaced. The statue underwent a restoration , funded by foundations and other private donations. For the sculpture's 50th anniversary, funds from operational savings and energy conservation totalling $170,000 were used for restoration improvements. In 2018, the sculpture had routine maintenance completed which involved touching up the green patina, as well as the gold figures and sphere. On September 21, 2018, the City of Detroit had a ceremony to celebrate the 60th anniversary of the sculpture. In 2017, Spirit Plaza was initially constructed and subsequent upgrades completed in 2019 and paid for by $800,000 in bond funds have yielded a 20,000 square-foot plaza with a playground, stationary musical instruments, tables, chairs, vehicle charging stations, and drinking fountains. In 2013 art dealer and art historian Eric Ian Hornak Spoutz was quoted in The Detroit News stating that the value of the statue is in excess of $1 million. In 2017, the Detroit-Wayne Joint Building Authority said that based on the most recent appraisal of the sculpture, it would cost $6 million to repair significant damage. Uses as a community symbol As one of Detroit's most easily identifiable landmarks, a sketch or depiction of the statue appears as the central element of most of the logos of Detroit's city departments and services. During the 1980s, a facsimile of the statue was featured on the Detroit Police Department's insignia and on the sides of its police cars. An image of the statue appears on the "Spirit of Detroit Award" certificate, which is issued by the Detroit