“It was a complete surprise,” said Brian Howland, resident engineer for the Massachusetts Bay Transportation Authority. “We knew there were mosaics down there, but that there was another complete ‘Scollay Under’ sign — that was completely unknown.”

And there, just beneath the grimy placard, a pristine mosaic of white and burgundy tiles was revealed: “SCOLLAY UNDER.”

As construction crews worked Monday to demolish many 1960s vestiges during the two-year rehabilitation of the Government Center MBTA Station, they pulled back a dingy Blue Line sign, a station feature sure to be replaced.

The mosaic dates back to the opening of the Scollay Under platform in 1916, which was built years after the construction of Scollay Station in 1898. For fifty years, the mosaic was hidden behind the newer, garish Government Center sign — unable to be enjoyed by the public, but also protected from deterioration.


“It’s really a piece of craft. It’s a beautiful, creative thing,” Howland said, adding that construction crews were careful not to harm the tiles as they removed the rest of the Government Center sign. “As soon as they saw it, they knew it was something important.”

There is a twin mosaic on the other side of the platform — on the outbound side, toward State Street Station — worse for wear after years of display. The newly revealed Scollay Under sign, which is on the side of the platform that leads to Bowdoin Station, is largely unscathed.

Government Center was closed last month for a two-year renovation project that will make the station accessible for people with disabilities. It will reopen with a new glass entryway on City Hall Plaza.

Until it reopens, trains will continue traveling through the station, but commuters are not allowed to board or disembark there.

Howland said project designers are hoping to keep the just-discovered mosaic in its current place and retain the portion of the wall that holds it as a memento of construction that dates back a century.


“The current plan is to. . . keep the area around the mosaic sign intact,” MBTA spokesman Joe Pesaturo said.

The Scollay Under mosaic on the outbound side will be removed tile by tile, cleaned, restored, and reinstalled elsewhere on the platform.

While some might be surprised that 1960s architects would choose to disguise a train station’s most historic elements and details, that approach was typical of midcentury renovations, Howland said.

More than a few vestiges of Boston transit history have only recently returned to the public eye: In 2005, during a renovation of South Station, a piece of wall was pulled away to reveal a blue-and-white terrazzo-tiled sign for “South Station Under.” That sign had a significant amount of damage, and its chipped tiles had to be restored before it could be displayed.

“I’m no architectural historian, but I would say that back then in the ’60s, there was a lot of thought into covering up things that were historic,” Howland said. “There was not as much of a sense of appreciation for that kind of stuff as there is now.”

Bradley H. Clarke, a local transit historian, said it would be exciting if the T made any other discoveries as it strips away parts of the station, but he doubts there is much more to uncover.

Clarke said that transit officials in the 1960s did a poor job of protecting artifacts during that renovation, and many vintage signs and pieces of bronze work vanished in the process. Few noteworthy features from the late 1800s remain.


“I doubt they’ll find anything major,” Clarke said, “but I’d love it if they do.”

Martine Powers can be reached at martine.powers@globe.com. Follow her on Twitter @martinepowers.

Correction: An earlier version of this story misstated the age of the mosaic. It dates back to the opening of the Scollay Under platform in 1916.