The Powerhouse Parramatta opening arrives this weekend, when the new museum throws open its doors for the first time. Announced in 2014, the project arrives with a 23-day opening festival of performances, parties, talks, screenings and workshops, of which 65% is free.

The journey has not been without turbulence. The $915m project came under scrutiny through a New South Wales Treasury investigation into governance and procurement allegations, and in late August – 10 weeks before opening – CEO Lisa Havilah was stood down while the investigation unfolded. Critics, led by former staff and trustees, have lamented what they see as the neglect of the museum's Ultimo site.

A lattice exoskeleton of 1,300 pieces

Dubbed the 'Opera House of western Sydney', the Moreau Kusunoki and Genton-designed building is defined by a white lattice exoskeleton of 1,300 individual pieces wrapping 30,000 sq metres of interior space.

• •The steel frame encases two towers and uses 12,000 tonnes of steel.
• •That structure allows column-free exhibition spaces up to 18m high, including the largest in Australia.
• •Interior walls are finished in a pale, textured render made from 600,000 locally, sustainably sourced crushed oyster shells.

Five exhibitions and 1,600 objects

Five opening exhibitions launch the museum: a tribute to space and flight, a celebration of the shopping mall, a kids' exhibition on the dark, and an Es Devlin showcase, among others. More than 1,600 objects from the 500,000-strong collection appear, supplemented by around as many loans.

The flagship, and the only exhibition adults pay for, is Task Eternal ($30, $20 concession, free for 16 and under). It fills a 2,000 sq metre main hall with 18-metre ceilings and draws on excerpts from US science fiction author Ted Chiang's short story Tower of Babylon.

• •Hero items include da Vinci sketches, a bumarang collected from Burramatta/Parramatta in the early 19th century, a 1960s Apollo 'boilerplate' command module and the spacesuit worn by Leonard Nimoy's Spock in Star Trek.
• •Also on show: Lawrence Hargrave's 19th-century flying rigs, a Skylark research rocket deployed at Woomera in the 70s, and a fully functional retro Rocket Playground from the 1960s.
• •For children aged 4 to 12, The Dark is set in a replica meteorite more than 22m long, entered via a tunnel and glowing chambers holding over 800 objects – including the first item the museum collected, in 1882: a jar of peas, and a heart-emblazoned shirt worn by Leonardo DiCaprio in Baz Luhrmann's Romeo + Juliet, the museum's most Googled object. No photography is allowed and phones must be bagged.
• •Atop a tower, James Turrell's 'ganzfeld' installation admits eight viewers at a time; a Turrell-inclusive ticket costs $40 for adults and $10 for kids.

First Nations water projects

On the eastern building's third floor, Overflow is a 16-metre high-definition LED display of short films by director Ivan Sen featuring seven Indigenous organisations from NSW. The museum invested an undisclosed sum in the seven organisations, funding projects including tagging marine life in Gamay (Botany Bay), clearing rubbish and mitigating pollution in the Parramatta River, and removing European carp from the Barwon River in Brewarrina.

Beau James, Powerhouse's director of First Nations, noted the building sits on a flood plain.

Es Devlin's Australian debut

The Es Devlin exhibition marks her Australian debut, presenting five recent works across four main rooms by the designer whose portfolio spans theatre, fashion and arena concerts including tours for Beyoncé, U2 and Lady Gaga, as well as Olympic ceremonies and Super Bowl half-time shows. A mirror maze represents the 'arterial geometries of lungs and trees', while her Collective Portrait centres on a room with a 24m table where strangers sit for 15 minutes drawing each other.

Devlin also created a sixth temporary work, an Australian iteration of her 2022 Come Home Again, featuring hand-drawn sketches of 244 endangered local species, with choral tributes performed at dusk most nights through November. She hopes the ritual of these evensong gatherings will keep drawing people back, calling it "like a beacon".

She describes Powerhouse Parramatta as a 'magnificent' building with 'astounding' opening exhibitions, and predicts it will become a destination for visitors from far and wide.

The museum opened to the public on Saturday; Devlin's choral evensong performances continue at dusk most nights through November.