The Carbuncle Cup was an architecture prize, given annually by the magazine Building Design to "the ugliest building in the United Kingdom completed in the last 12 months". It is intended to be a humorous response to the prestigious Stirling Prize, given by the Royal Institute of British Architects. The award was inspired by the Carbuncle Awards that Scottish architecture magazine Urban Realm, formerly Prospect, had been presenting to buildings and areas in Scotland since 2000. The event was last held in 2018.