ENTERTAIN — make the roof span part of the show

Rondo, today's Winning Group Arena, was a very different assignment. Ivan Ruller's circular multipurpose hall developed through the 1970s and opened in 1982 for winter sports and other mass events. Here technical performance is visible architecture: a huge roof has to cover an uninterrupted arena while thousands of people enter, circulate and watch the event below. Instead of hiding engineering, the building lets structure contribute to its civic identity. Walk around enough of the perimeter to understand the circle rather than judging it from one facade. The job is collective attention: architecture must hold a crowd, give it a focal centre and keep the span overhead out of the way.