Boston Marathon Finish Line Bridge Under Construction

BOSTON (CBS) -- Construction of the Boston Marathon finish line bridge was underway Saturday on Boylston Street.

The work is in preparation for the 120th annual Boston Marathon on Patriots' Day on April 18.

The bridge is home to TV cameras and photographers, as well as the WBZ-TV broadcast team. Marathon runners see it as soon as they turn onto Boylston and that's when they know they've nearly completed the race.

It's unclear when the project will be completed before race day.