It's fascinating the way a building - and our perception of it - can potentially be transformed in a single afternoon. In this case the edifice in question is the Royal Opera House. This past weekend that illustrious (and, some might say, elitist) institution flung open its doors and invited us to enter and explore its public spaces from top to bottom.

The occasion was Deloitte Ignite, a cornucopia of free performances and experiences merging the arts and sensory stimulation. The business advisory firm has committed funds for five such annual events, each curated by a different artist associated with Covent Garden. The ROH's innovative resident choreographer, Wayne McGregor, was responsible for the inaugural choices.

I spent nearly five hours at the ROH on Saturday afternoon trying (and, not unhappily, failing) to take it all in. A few of the dozen items on the agenda - an overcrowded chocolate-tasting lecture by representatives from Green and Blacks, for instance, or Ray Lee's sublimely heady sonic performance-installation Siren - happened only at specific times. Others, even if they entailed queueing up, were ongoing.

A sense of discovery permeated the premises. The visual artist Julian Opie hung an elongated, digital hip-swinger in the box office area. A small squadron of uncannily alert, robotic face mirrors by the experimental design collective rAndom International dominated a corner of the Paul Hamlyn Hall, while up on the terrace patient punters were treated to hand massages using Jo Malone's intoxicating scented creams. McGregor's crack at Ignite was anchored by showings of Proprius (derived from proprioception, referring to a sense of self). Unleashed on a sun-drenched stage wedged into a corner of the Piazza, this lengthy but rewarding - and at times explosive - dance united members of his superb company, Random, with diligent, disciplined young people from London and the East of England. It was all good stuff, and worth looking out for next year.

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