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.