(CNN) It was a typical day at work for construction crews in Boston.

They were digging on a plot of land planned for a 400,000-square-foot office building, but little did they know they were about to unearth a historic find: the remains off a 50-foot wooden ship from the mid- to late 1800s.

"This is the first shipwreck that I know of in Boston discovered in filled land," city archaeologist Joe Bagley told CNN affiliate WBZ . "This is the largest and most significant by far."

The Skanska construction crew stumbled across the discovery in the Seaport District last week and immediately halted construction.

Photos: Shipwreck found in Boston Construction crews discovered a shipwreck last week in Boston. Hide Caption 1 of 5 Photos: Shipwreck found in Boston The vessel was found 25 feet below grade near Boston Harbor. Hide Caption 2 of 5 Photos: Shipwreck found in Boston On Wednesday, May 25, city archaeologist Joe Bagley started excavating the historic find. Hide Caption 3 of 5 Photos: Shipwreck found in Boston The vessel is believed to have been hauling barrels of lime some time in the latter half of the 19th century. Hide Caption 4 of 5 Photos: Shipwreck found in Boston "This is the first shipwreck that I know of in Boston discovered in filled land," Bagley told CNN affiliate WBZ. "This is the largest and most significant by far." Hide Caption 5 of 5

How did it get on land?

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