1988
Thomas Krens succeeds Messer as director of the Foundation. Krens takes up an expansion program already underway in New York, which will include an annex designed by Gwathmey Siegel and Associates Architects, LLC., and initiates planning for a comprehensive restoration of the Wright building.

1990
The Wright building is closed to the public so that the restoration and expansion can begin. Over the next two years, masterpieces from the collection are exhibited in a triumphant international tour to Venice, Madrid, Tokyo, Australia, and Montreal.

1991
Through purchase and gift, the Guggenheim Foundation acquires the Panza Collection of Minimalist and Conceptual Art, giving depth to the Guggenheim’s permanent collection with works by American postwar masters Carl Andre, Dan Flavin, Bruce Nauman, Robert Ryman, Richard Serra, and many others.

1991–92
The Robert Mapplethorpe Foundation gives the Guggenheim Foundation 200 vintage photographs by Mapplethorpe, as well as a grant to launch a photography program. Contemporary photography quickly becomes a major area of collecting, and within a decade the Guggenheim Museum is able to mount significant major exhibitions based on its holdings.

1992
After a three-year restoration of its interior, the Solomon R. Guggenheim Museum reopens to great acclaim. An eight-story annex, designed by Gwathmey Siegel and Associates Architects, LLC. opens simultaneously.

2005
Restoration of the exterior of the Frank Lloyd Wright building begins. Although overall in good structural condition, the building requires exterior work to infill cracks, expose and treat corroding steel, repair and protect all of the concrete work, and perform some structural interventions on the 6th-floor Rotunda walls. The restoration is scheduled to be finished in time for the 50th anniversary of the museum’s opening in 2009.

2008
After over three years of significant restoration work, thanks to Peter B. Lewis, former Chairman of the Board of Trustees, the City of New York, the State of New York, and other donors, the Solomon R. Guggenheim Museum sheds its scaffolding to reveal a restored facade and interior improvements. In celebration of the restoration, the Foundation commissions artist Jenny Holzer to create a site-specific light projection for the facade of the Guggenheim entitled For the Guggenheim.