The Chicago art collector and retired plastics mogul Stefan Edlis and his wife Gael Neeson have donated a collection of 42 pop and contemporary artworks worth a combined $500 million to the Art Institute of Chicago, the Wall Street Journal reports. According to the museum, it is the largest gift in its history.

The gift includes nine seminal silkscreens by Andy Warhol, three Jasper Johns paintings, two Roy Lichtenstein canvases, four Gerhard Richter paintings, and a Cy Twombly sculpture.

“Chicago in general and the Art Institute in particular have been historically poor in collections of classic pop art, and this in one single gift changes that forever,” James Rondeau, curator of contemporary art at the Art Institute, told CT Now. 

“This takes our contemporary collection from good to extraordinary,” Douglas Druick, president and director of the museum, told CT Now. “It’s not simply names and numbers, it’s the works themselves. It’s the best of the best. These are incredibly passionate and discerning collectors who have very ably refined their collections over time,” he enthused.

Druick explained that the museum made a series of assurances to secure the collection. These include a promise to hang the works in the institution’s 6,000-square-foot Renzo Piano–designed wing for the next 25 years, and within the museum’s greater collection for an additional 25 years.

This is the second major gift that “the world’s favorite museum” has received this year, following Barbara Levy Kipper’s substantial donation of Asian art in January (see Art Institute of Chicago Receives Trove of Asian Art and The Art Institute of Chicago Is the World’s Favorite Museum).