Over a span of 400 years, dukes and duchesses of the UK’s aristocratic Cavendish-Bentinck family acquired a private body of art known as the Portland Collection. On March 20, pieces from the family’s 5,000-work-strong archive will finally be shown to the public with the opening of the collection’s official gallery.

The collection is managed by the Harley Foundation, a charitable trust formed by the Duchess of Portland in 1977 to support the visual arts. The new 9,580-square-foot gallery, housed in a new facility that was once used to train racehorses, is an addition to the Harley Gallery, which is located on the Welbeck Estate‘s rolling, 15,000-acre plot along the borders of Nottinghamshire and Derbyshire.

Michelangelo, Madonna del Silenzio (circa 1538). Photo courtesy of Mark Asher/The Harley Gallery.

“We knew there was this fantastic collection,” William Parente, grandson of the seventh Duke of Portland, told the Guardian. “I’d grown up with it, and we all felt a bit uncomfortable that we were the only ones who saw it.” In an effort to reinvigorate the local community’s cultural scene, admission to the gallery is free.

Due to the tremendous size of the estate’s collection, the gallery will host three exhibitions a year. Oil paintings will be displayed in a room with a long skylight, providing ample natural light, while miniatures and light-sensitive objects will be shown in the adjacent treasure gallery.

Among the collection’s highlights are a rarely seen Michelangelo chalk drawing titled Madonna del Silenzio (circa 1538), a pearl earring worn by Charles I during his execution, and a Cartier tiara made for Winifred, a late Duchess of Portland.

The Long Gallery by Hugh Broughton Architects.
Photo: Courtesy of Hufton+Crow via the Harley Gallery.

It’s worth mentioning that this isn’t the first time we’ve seen private entities open up their collections to the public. Just last month, collector Désiré Feuerle announced plans to open a private museum in Berlin. In 2015, billionaire Bruce Berkowitz got approval from the city of Miami to build a private museum for his collection, including a massive Richard Serra sculpture and a James Turrell installation.