26 September 2011 Last updated at 20:49 ET Share this page The obelisk was erected in honour of first US President George Washington The Washington Monument is to remain closed indefinitely to visitors, as engineers assess the damage to the obelisk caused by August's earthquake. The National Park Service said numerous cracks had been found in the iconic landmark in the US capital. But it said that the 555ft (169m) monument was "structurally sound". The agency added that experts would now begin checking what needed to be mended to make sure the obelisk was safe before the public was allowed back in. "The good news: The monument is structurally sound and is not going anywhere," said Bob Vogel, superintendent of the National Mall for the National Park Service. Security camera footage shows tourists fleeing the monument Mr Vogel also said he hoped a repairs timetable would be announced next month. Officials have made public CCTV images showing tourists seeking cover after the 5.8-magnitude earthquake shook the monument's observation deck near the top. The world's tallest stone structure was erected in honour of first US President George Washington in 1884. The 23 August tremor rattled the US East Coast, but caused no deaths or serious injuries.