The official kick-off of the construction phase of the Green Line Extension project took place at a groundbreaking ceremony on Monday at Union Square in Somerville.

The event coincided with the $225M release of funding for the project by the federal government.

In attendance were U.S. Department of Transportation Secretary Elaine L. Chao, FTA Acting Administrator K. Jane Williams, Gov. Charlie Baker, U.S. Rep. Michael E. Capuano, U.S. Rep. Katherine Clark, and Somerville Mayor Joseph A. Curtatone.