On September 7 , 2004 the monument closed for a $ 15 million renovation , which included numerous security upgrades and redesign of the monument grounds by landscape architect Laurie Olin . The renovations were due partly to security concerns following the September 11 attacks and the start of the War on Terror . The monument reopened April 1 , 2005 , while the surrounding grounds remained closed until the landscape was finished later that summer
September 11 attacks
September 11 attacks
Washington Monument