The Old John Hancock Building, now known as the Berkeley Building, is known for its weather beacon which can be seen at its summit. The 36- story, 495 foot Back Bay building was completed in 1947 and was designed by Cram and Ferguson. From its completion until 1964 it was the second tallest building in the city of Boston, but has fallen to its current spot at 18th tallest in the city since then.

Prior to March 2003 the building belonged to the John Hancock Insurance company, but was sold to Beacon Capital along with the Stephen L. Brown building and the John Hancock Tower. In 2006 the Berkeley and Brown buildings were reacquired by the John Hancock Insurance company.

In 1950 the building was topped by the weather beacon that still stands there today. The light atop the beacon flashes different colors according to the weather prediction for the day, which can be remembered by this handy poem:

Steady blue, clear view
Flashing blue, clouds due
Steady red, storms ahead
Flashing red, snow instead

During baseball season, a flashing red means that the Red Sox game has been cancelled due to weather conditions. In 2004 after the Red Sox won the World Series, the lights flashed red and blue and another line was added to the poem, “Flashing blue and red, when The Curse of the Bambino is Dead!” This change in lighting was the first time the color scheme changed since the tower was lit in 1950.

The light was shut off from 1973 until 1983 during an energy crisis to set an example, but has been flashing ever since.