The exhibit opens with a painting of lower Manhattan shrouded in thick gray smoke under a blue sky, the Twin Towers having both collapsed after being rammed by hijacked passenger jets.Bush, who had taken office less than eight months earlier, has "returned to this defining moment in American history with brush and canvas, painting the symbols, the people, and the embraces that have stayed with him since," the exhibit's introduction says.It is the latest special collection produced by the 80-year-old former president, who took up painting a few years after leaving office in 2009, with previous exhibits dedicated to portraits of veterans of his post-9/11 wars and American immigrants.Bush himself is featured in half of the paintings, which include iconic moments, such as when he was informed by staff that a second plane has struck the World Trade Center, and more subtle scenes like him taking the hand of his father, former president George H.W. Bush.The American flag is a recurring theme in the surprisingly colorful series, displayed at the Bush Presidential Library in Dallas, Texas.

US president George W. Bush (L), now an avid painter, visited 'Ground Zero' in lower Manhattan three days after the attacks of September 11, 2001 © Paul J. RICHARDS / AFP/File