two-story storage vault, a spacious library, and two interior grassed courts that insulated occupants of the library and administrative offices from heavy traffic passing nearby. On November 17, 1998, museum trustees announced plans to expand the museum yet again. Museum personnel had been in discussion with Philip Johnson for some time regarding the need to alter Johnson's 1977 addition. Johnson's solution was to demolish both the 1964 and 1977 additions and create a new, much larger structure behind the 1961 building. Philip Johnson spearheaded the new design in collaboration with his partner Alan Ritchie. It would be one of the last projects on which Johnson worked. In August 1999 the museum was closed to the public for an extended period while the 1961 building was refurbished, the 1964 and 1977 additions were removed, and the new addition constructed. The current museum building reopened to the public on October 21, 2001. The 2001 expansion, which increased the museum's available space by 50,000 square feet, rests on the same footprint as the earlier additions. It is clad in dark Arabian granite so as to recede visually from the light-colored shellstone of the 1961 building. The expansion's most arresting feature is a centrally located atrium, rising fifty-five feet above the floor and topped by a curved roof with side windows, referred to as the Lantern. The atrium's interior walls are clad in the signature shellstone. A double stairway gives access from the atrium to a complex of second-floor galleries where selections from the museum's permanent collection, along with special exhibitions, are on display. In this new alignment, most of the galleries in the 1961 building, including the mezzanine area where the library and offices were once located, are used for rotating exhibitions of paintings and sculpture by Remington and Russell from Amon G. Carter's original collection. Other features of Philip Johnson's 2001 expansion include a 160-seat auditorium, complete with distance-learning technology; climate-controlled vaults for both cool and cold photography storage; laboratory space for the conservation of photographs and works on paper; a research library and archives storage facility; and a museum bookstore. In the summer of 2019, the museum building was closed for a renovation of the building and the galleries. The Boston-based architecture firm Schwartz/Silver Architects oversaw the renovations; unlike the 1977 and 2001 closures, there was little alteration to the museum building's structure. Instead, the museum redesigned parts of the interior