MT BACK BAY ONE LLC
2 office properties in Boston recorded to an owner mailing to 10 ST JAMES AVE 10TH FLR, BOSTON, MA. single entity
At a glance
MT BACK BAY ONE LLC is recorded as the owner of 2 office properties (2 parcels) in Boston, totalling 894.3K sq ft of building area with $451.9M of assessed value. The owner's tax bills go to BOSTON, MA.
County assessment roll
Properties
| Building | Submarket | Sq ft | Assessed | Last sold | Tenants |
|---|---|---|---|---|---|
| 319 Stuart ST | Boston | 610.7K | $340.6M | $673,000,000 · Jan 2017 | 0 |
| 6 ST JAMES AV | Boston | 283.7K | $111.2M | $673,000,000 · Jan 2017 | 0 |
How this group was built. All of these parcels are recorded to one owner entity.The county records an owner and a mailing address for every parcel; this page collects the office parcels whose owners mail to the same address, and counts buildings rather than parcels using the county's own condo-to-building link. Lease terms, rents and the identity of a manager acting for the owner are not public records and are not shown.
Where are MT BACK BAY ONE LLC's office buildings?
All 2 properties are in Boston.
The largest is 319 Stuart ST in Boston at 610.7K sq ft over 19 floors.
Recorded build years run from 1913 to 2001.
How large is this portfolio within Boston's office market?
Its 894.3K sq ft is 1.27% of the 70.4M sq ft of office building area on the Boston roll.
Its $451.9M of assessed value is 1.37% of the metro's office total.
It holds 2 of the metro's 1,046 office buildings.
2 of its parcels carry a recorded sale price; the most recent was 319 Stuart ST in Jan 2017 for $673,000,000.
Frequently asked questions
How many office buildings does MT BACK BAY ONE LLC own in Boston?
2 office properties (2 parcels) on the Boston roll, counted by building rather than by condo parcel.
What is MT BACK BAY ONE LLC's largest office building?
319 Stuart ST, Boston — 610.7K sq ft, assessed at $340.6M.
What are MT BACK BAY ONE LLC's office properties worth?
Their combined assessed value on the current Boston roll is $451,866,200. Assessed values are taxable-roll figures, not market prices.
When did one of MT BACK BAY ONE LLC's Boston office properties last change hands?
The most recent recorded transfer among these parcels is 319 Stuart ST, Jan 2017, for $673,000,000.
Related
Everything here comes from public records, and public records go stale. If you know better, say so.
Data provenance — public records only
- Boston — MassGIS L3 standardized parcels with the city assessment roll (owner names, mailing addresses, stories, assessed values, last recorded sale). Boston publishes no universal business roll, so no tenant layer is possible from public records here.
Every fact on this page is drawn from the government records above — no listing sites, no scraped platforms, no third-party images. Facts from public records are uncopyrightable; each tenancy row carries its source and match confidence. Records can lag reality — a business-tax receipt or registration at an address is evidence of occupancy, not a lease confirmation.
Dataset updated . Derived from public data sources.
About this data
Source: MassGIS L3 standardized parcels with the city assessment roll (Boston), as published September 20, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: BuildingCensus, “MT BACK BAY ONE LLC — Boston office property holdings”, https://buildingcensus.com/offices/boston/owners/mt-back-bay-one-llc-ce9ca3 (data as of September 20, 2026).