Two steel columns, from the North Tower, known as tridents. They are the first artifact that visitors encounter as they make their descent into the 9/11 Memorial Museum and the only one visible from the 9/11 Memorial. www.911memorial.org/visit | National September 11 Memorial & Museum

Descending from the 9/11 Memorial into the 9/11 Memorial Museum, visitors encounter 110,000 sq. ft. of museum space and historic artifacts set within the remnants of the Twin Towers. www.911memorial.org | National September 11 Memorial & Museum