Congratulations to Reg Ellis & Associates of Chipping Campden in Gloucestershire, who managed to spot all six changes we'd made to the building below, Ronchamp. For the chance of winning a bottle of champagne, readers are asked to spot the deliberate changes we've made to the building above, Schröder House in Utrecht. Clue: there are eight changes. Post your answers, to arrive by first thing Monday morning, to Ring the Changes, 151 Rosebery Avenue, London EC1R 4GB, or fax 020 7505 6701. The first correct entry pulled out of the hat wins a bottle of bubbly.