Conversation so far:
Who is Paul Rodgers, the singer?
Paul Rodgers is an English singer who was the vocalist for Free and Bad Company.
What did the band Queen do with Paul Rodgers?
Two of the four members of the British rock group Queen proposed a collaboration with Rodgers, in which he would sing lead vocals on a European tour.
Is the UK Music Hall of Fame the only place the band Queen and Paul Rodgers performed together?
Queen + Paul Rodgers Tour was a world concert tour by Brian May and Roger Taylor, joined by Paul Rodgers under the moniker of Queen + Paul Rodgers.

Question: When was their world tour?
Self-contained rewrite: When was the band Queen's world tour with Paul Rodgers?