Boston and Maine station, Haymarket square, 1866.
The Boston and Maine railroad ran from Boston to Portland, and over the years, through expansion and consolidation, would cover New Hampshire and stretch across northern Massachusetts to New York and extend south to Springfield. The photograph above shows the station that sat on Haymarket square. This was the only rail line from north of Boston that ever extended so far into the city.
Boston and Maine RR station (marked in red), Haymarket square, 1852.
This map fragment shows the location of the station. Please notice the triangle (the Bullfinch Triangle) formed by Merrimack, Causeway and Charlestown streets. Causeway street was built along the line of the old dam across the North End cove. Merrimack and Charlestown streets approximate the curving path of the original shore of the cove, and the land within the triangle thus formed was all made land, built with fill taken from Beacon Hill. On the far side of Causeway street, we see other railroad stations (to be discussed later), wharfs and docks, and other streets laid out on filled land.
The railroad tracks ran between Canal and Haverhill streets from Causeway street to the station. The tracks were laid out on top of the filled canal - appropriately - that had been built through the Bullfinch Triangle to Haymarket square. Before the building of the railroads, the Middlesex Canal had carried freight south from the Merrimack river to the port of Boston. The canal through the filled land of the old cove was considered an extension of the Middlesex. With the coming of the railroads, the canal was no longer profitable or necessary, so the Boston extension could be replaced by the trains.
In time, the Haymarket station would be replaced by a new one on Causeway street, which I'll look at later.