The Washington Monument was closed on August 23, 2011, following a rare and significant 5.8-magnitude earthquake centered in Mineral, Virginia. The seismic activity caused substantial structural damage to the 555-foot marble obelisk, including over 150 cracks throughout the structure and several large pieces of stone breaking off from the pyramidion at the very top. Debris fell both inside the monument and around the exterior plaza, fortunately while the monument was being evacuated. The National Park Service had to launch a massive, multi-year restoration project that cost $15 million, half of which was funded by a private donation from philanthropist David Rubenstein. The repairs involved complex "re-pointing" of the mortar and the installation of stainless-steel plates to reinforce the damaged sections. The monument remained closed to the public for nearly 33 months, finally reopening in May 2014 after a meticulous inspection and repair process that ensured the landmark was seismically stable for future generations.