Birmingham's new library has been lit up in claret and blue for Christmas.
The festive illuminations on the £189m building in Centenary Square pay homage to local football club Aston Villa's famous colours.
A spokesman for the library described the link-up with the club as "exciting and eye-catching". The colours are due to remain until the new year.
But fans of Villa's local rivals, Birmingham City, say the move is "massively unfair".
Villa officials approached the library with a view to celebrating the success of the two organisations.
Brian Gambles, director at the Library of Birmingham, explained: "Villa's reputation in the football world makes a nice symmetry with the new and exciting library.
"We were only too happy to partner with them on this festive project."
Paul Faulkner, Aston Villa chief executive, who is also a trustee of the library, said: "The library is a striking focal point - even more so now it has adopted our famous club colours for a few weeks."
Aston Villa boast a phalanx of famous
But some Birmingham City fans have taken issue with the library's link-up.
Nick Glynn, chairman of the Birmingham City East Midlands Supporters Club, said: "Aston Villa isn't the only football team in this city, and I think there needs to be a rethink about what has happened, really.
"The building should have at least been lit 50-50; half our colours, half Aston Villa colours.
"This is a public building, so maybe the public as a whole should have been consulted before this went ahead."
Birmingham City supporter, Darren Constable, 37, from Bloxwich, said: "I think it's massively unfair, to be honest.
"It's as if they are saying Aston Villa is the only club associated with the city, which it isn't."
Villa boast celebrity fans including Prince William, David Cameron and Tom Hanks, and have won seven league titles, seven FA Cups, five League Cups and the European Cup.
Birmingham City's famous supporters include TV funnyman Jasper Carrott, Homeland actor David Harewood and ELO's Jeff Lynne.
Blues have won two League Cups, including in 2011.