A major private contemporary art collection with a value estimated at $400 million is being donated to the Art Institute of Chicago by local philanthropists Stefan Edlis and Gael Neeson, in what the museum is calling the largest gift of art in its history and a coup for the institution and the city.

Numbering 42 pieces, stocked with iconic works by Andy Warhol, Jasper Johns and many other instantly recognizable names and spanning a time period from 1953 to 2011, experts called it one of the most significant collections of its kind in the world.