The hotly-anticipated Marciano Art Foundation – a new art museum created by wHY Architecture and Design – opens tomorrow (25 May) in Los Angeles’ Windsor Square; within one of the city’s most unusual buildings.

The 100,000sq ft (93,000sq m) arts space is housed inside the secretive former Scottish Rite Masonic Temple, designed by Californian painter and architect Millard Sheets in 1961.

wHY’s founding partner, Kulapat Yantrasast, was tasked reinterpreting the building; adding various interior gallery spaces, a climate-controlled art archive, a bookstore, a café, and an outdoor sculpture garden, while preserving as much of Sheets’ original design and layout as possible.

“The building was obviously well built, and the integral pride and spirit of Masonry symbolised and celebrated,” said Yantrasast. “One could not imagine a better building type to convert into an art space, with all the high-ceiling rooms, wide-span structures, and extensive wall spaces with few windows.

“However, the sense of closed exclusivity and esoteric social identity could potentially send it towards yet another isolated art bunker. We wanted to combat this perception, and, despite the building’s solid presence, embrace Los Angeles in its own way.”

The interiors have been simplified, modernised and reorganised, but temple’s grand mosaic has been restored and the Masonic statues surrounding the building have been retained.

Explaining why he wanted to keep some of Sheets’ more flamboyant flourishes, Yantrasast said: “Today we have more and more art, but fewer unique places to see it or and make it. Now, the often-cited accusation that Los Angeles is ambivalent about embracing its history has found the best site to link the past and present.”

The Marciano Art Foundation has been funded by brothers Maurice and Paul Marciano, who moved to LA from the south of France in 1981 and founded the Guess? denim fashion brand.

The pair have opened the museum as a free place for the public to enjoy their diverse collection of contemporary art, which contains more than 1,500 works by over 200 artists and covers the mediums of painting, sculpture, photography, installations, performance, film and digital work.