wed to use the rotunda for flying miniature aircraft during the weekends. The rotunda continued to host other events like the annual Alfred I. duPont-Columbia University Awards for news broadcasters. The LPC designated the first-floor interior as a city landmark in 1981. In addition, the library was added to the National Register of Historic Places as a National Historic Landmark in 1987. In 2001, Columbia began to renovate Low's roof and add new mechanical systems to plans by David Paul Helpern Associates. The work was projected to cost $14.5 million, and the installation of the new mechanical systems would enable Columbia officials to remove mechanical equipment on the roof. At the time, the building was still open to the public on weekdays from 9 a.m. to 5 p.m. Through the 21st century, Low continued to be the location of large events such as protests and rallies. For example, students conducted a sit-in and a "sleep-out" in 2016 to demand d ivestment from fossil fuel companies, and a chapter of Extinction Rebellion protested in the building in 2019. Critical reception The 1954 Columbia University bicentennial stamp, depicting Low Library Low Library was intended not only to symbolize Columbia's new campus but also to serve as a functioning administrative center. A 1995 article from the journal Library Columns said that the cornerstone of the library symbolized the cornerstone of the entire campus "not only architecturally, but philosophically and philanthropically". Some early publications praised the design; one source said the library was "a utilitarian scheme artistically carried out", and another ranked the library "among the foremost in the world". In 2010, the AIA Guide to New York City described Low Library as "Columbia University's most noteworthy visual symbol" and a "dignified centerpiece for the campus". Conversely, the Real Estate Record and Guide, b elieving Low to be patterned after a French church by "the architect Rumpf", criticized the design as being "plagiarized" from the older church. Montgomery Schuyler, who resen