Grecia is the name of the third canton in the province of Alajuela in Costa Rica. The canton covers an area of 395.72 square kilometres (152.79 sq mi), and has a population of 69,703. The capital city of the canton is also called Grecia.
The canton lies among ridges and valleys on the southwestern slope of Poas Volcano. One area is completely separated from the remainder of the canton by the Cordillera Central (Central Mountain Range). Known as Río Cuarto, this area lies on the Caribbean Plain, and is intended to form its own canton at some unspecified future date.
The Río Poás and the Río Prendes establish a large portion of the eastern border of the elongated canton, with the Río Sarchí serving the same purpose on its western edge. The Río Grande is the southern border.