surface line across the center of town was politically impossible and prohibitively expensive. Building around the outskirts of town would have required massive regrading and bridging, as the terrain is extremely hilly and the line would cut across every watershed flowing into the harbor. As a temporary expedient, traffic was handled through Baltimore on carfloats across the Patapsco River / Baltimore harbor and port from Canton to Locust Point, but it was clear that a direct connection would have to be built. The route the B&O chose started from the existing end of track at Camden Street Station, at the west end of "The Basin" (modern Inner Harbor) of the Northwest Branch of the Patapsco River. A tunnel was constructed directly under Howard Street, heading north–south until just before it crossed the existing PRR line. At the north portal of the tunnel, Mount Royal was constructed between 1891 and 1896. The track then curved around the northwest corner of the center city going east, passed through six other (much shorter) tunnels, continuing across the northern outskirts of downtown, curving around the Northeast corner of the old City, finally heading southeast to meet the already constructed line just north of the Canton neighborhood and connecting with the East Coast route. The cost of construction drove the Baltimore & Ohio Railroad into bankruptcy shortly after the line opened in 1895, 68 years after the line was founded in 1827 as America's first passenger / freight railroad. Initially there were plans to build three new stations in Baltimore, but concern for interference with freight haulage and expense eventually reduced this to a single station at Mount Royal Avenue, just west by the Jones Falls stream, which opened on September 1, 1896. Lower-level platforms were added later at the east end of B&O's Camden Street Station in 1897. Howard Street Tunnel The Howard Street Tunnel, originally a long tunnel under Howard Street in downtown Baltimore, took four and a half years to build (1890–95) and was the longest tunnel on the B&O's system. Its construction cost $7 million (equivalent to more than $200 million in 2018) and required 2,400 workers. In the mid-1980s, the tunnel's original length of 1.4 miles or was extended an additional three-tenths of a mile (480 m) further south of its original Camden Station portal when the B&O successor CSX Transportation's mainline track east of the B&O warehouse was covered