Baião is a municipality in Porto District in Portugal. The population in 2011 was 20,522, in an area of 174.53 km². Baião received a charter from …Baião is a municipality in Porto District in Portugal. The population in 2011 was 20,522, in an area of 174.53 km². Baião received a charter from Manuel I on 1 September 1513. The present Mayor is Paulo Pereira, elected from the Socialist Party. The municipal holiday is August 24.