I managed B & M property records 1973-85. South of the Charles River, the B & M owned an area bounded by Nashua St. (where the O'Neill Bldg. is now), Causeway St. over to Beverly St. and the Charles River. The property came from its various component B & M, Boston & Lowell, Eastern and Fitchburg. In the 1920s, the B & M rationalized the terminal facilities and built both a hotel and office building. The hotel was owned by North Station Hotel Building and offices by North Station Industrial Building, both 100% B & M owned subsidiaries. The subsidiaries were most likely created because as non-railroad entities, they could be financed and operated without interference by the Interstate Commerce Commission. The B & M's financial plight starting in the 1950s led to a number of property sales. First to go was the Hotel Manger, renamed Madison and owned by 120 Trust. Next was the area from behind the hotel to Charles River from Track 12 through to Nashua Street. It went to North Station Auto Park. Tracks 12-23 and 3rd and 4th drawspans retired and paved. Both went about 1960-61. Area behind North Station Tracks 1-11 with exception of a walkway, maybe 20 ft wide also went for parking and Tracks 1-11 shortened by about 3 passenger car lengths. Also went to North Station Auto Park. North Station went to outfit named 140 Trust, 150 Causeway went to 150 Trust. North Station was the last to go, just before MBTA began subsidizing commuter service in January 1965. B & M retained a landlocked parcel encompassing Tracks 1-11 (Track 1 was used for storage for things like tool or salt cars; had no usable platform) about 3 passenger car lengths from North Station to Charles River. This was sold along with most B & M lines in Eastern Mass. to MBTA on 12/27/1976. Far as I know MBTA still owns it; it is not easy to dispose of their property, especially if financed with Federal grant money. 150 Causeway was built as a general office and exhibition hall. A lot of the furniture, plumbing and electrical suppliers were headquartered in the area of North Station when 150 was built (opened over Bunker Hill day wkend, 1930). When the circus came to town, the sideshow was over on the 1st floor of 150, I think. The double height allowed lots of room for unusual exhibits. Original B & M (the 1847 road) had its original Boston terminus at Haymarket Sq. When it constructed 1894 North Station, it sold from Causeway St. to Haymarket to Boston Transit Commission which then used it as north to south access to what is today's Green Line trolley subway. Check some older maps of North Station area and you'll note that some of the streets have railroad related names. Beverly, Haverhill, Lowell, Lancaster, Billerica, Nashua, Portland and Minot (named after the superintendent of the B & M who went over to the Erie and gave the first train order.).