Beneath Art Gallery of NSW, artist Mike Hewson has created a summer wonderland – BYO sausages and swimmers

<p>The Aotearoa New Zealand-born engineer-turned artist has created an art park of usable, social sculptures in the gallery’s underground Tank space, including a barbecue, playground and sauna</p><ul><li><p><a href="https://www.theguardian.com/newsletters/2019/oct/18/saved-for-later-sign-up-for-guardian-australias-culture-and-lifestyle-email?CMP=cvau_sfl">Get our weekend culture and lifestyle email</a></p></li></ul><p>It’s 4pm on a Thursday and I’m in a sauna underground at the Art Gallery of NSW, the hot, cedarwood-scented air a sharp contrast to the cool concrete cavern I’ve just stepped in from. Inside the gallery’s subterranean Tank – a 2,200 sq metre chamber that was once a second world war oil reservoir – Sydney-based artist Mike Hewson has repurposed a 1980s shed, gutting its faux-wood veneer and replacing it with western red cedar, from which he’s also created ornate church-style pews for seating. The windows are now stained glass; the floor and ceiling are lined with travertine tiles left over from one of the gallery’s older wings.</p><p>Clearly, this is no ordinary sauna. It’s one of several surprising sculptural works in Hewson’s playful exhibition The Key’s Under the Mat, opening this weekend. There are also change rooms, a steam room, barbecue, sound recording studio, laundromat and playground – all fully functional. You can borrow towels, shorts, slides and T-shirts for free, or bring your own swimsuit (no bikinis).</p><p><strong><a href="https://www.theguardian.com/newsletters/2019/oct/18/saved-for-later-sign-up-for-guardian-australias-culture-and-lifestyle-email?CMP=copyembed">Sign up for the fun stuff with our rundown of must-reads, pop culture and tips for the weekend, every Saturday morning</a></strong></p> <a href="https://www.theguardian.com/artanddesign/2025/oct/04/art-gallery-nsw-tank-artist-mike-h