Its history includes the refitting of USS Merrimack, which was modified to be the Confederate Navy ironclad CSS Virginia.

It measures 319.5 feet (97.4 m) in length, and is built of Massachusetts granite, stepped to allow access to and bracing of ships under repair.

[4] It may have been designed by Loammi Baldwin Jr., then the Navy's superintendent of drydocks, and its construction was overseen by William P. S. Sanger, a civil engineer.

[4] During the opening phase of the American Civil War in April 1861, Union forces were dispatched from Washington on the USS Pawnee to assist in destroying military assets as the shipyard was being abandoned; however, efforts to blow-up the dry dock were unsuccessful.

[7] The shipyard was then taken over by the Confederate Navy, which was a severe blow to the Union,[8] and it was here that USS Merrimack was modified to become the ironclad CSS Virginia.