Callison

Callison was an international architecture firm based in Seattle, Washington. Callison was founded by Tony Callison in 1975 and grew to 900 employees around the world prior to its acquisition by Arcadis NV in 2014. In October 2015, Callison was formally merged with another Arcadis subsidiary, RTKL Associates, to form CallisonRTKL headquartered in Baltimore, Maryland.