669-671 Atlantic Ave
669-671 Atlantic Ave is a 49-story building in Downtown Boston with 67% of its floor area within daylight reach of a facade. This screen estimates 1,019 homes and scores it 63 out of 100 for office-to-residential conversion suitability.
MA-7 & MA-8 · Screened 2026-10-04 · Worth a feasibility study
Where 669-671 Atlantic Ave is
Its block in Downtown Boston, drawn from Boston's own building outlines and street centerlines.
- Already housing
- Not screened
- 669-671 Atlantic Ave
This building does not pencil at default assumptions, even with a modeled RESIDE Act grant.
Across its 48 residential floors this building carries 463,611 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment.
Modeled conversion metrics for 669-671 Atlantic Ave, 2026-10-04.
| Suitability scoreWorth a feasibility study | 63 / 100 |
|---|---|
| Storiesfrom 590 ft aerial-survey height ÷ 12 ft floor-to-floor | 49 |
| Height bandsfloor plate by floor range, from the city's roof outlines | Floors 1–7: 46,237 sq ft · Floors 8–14: 39,151 sq ft · Floors 15–49: 24,798 sq ft |
| Floor platetypical floor, from the city outlines | 24,798 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 67% |
| Deepest interior pointviability threshold is 80 ft | 62 ft |
| Windowless coretypical floor; the building-wide total is in the text above | 7,029 sq ft |
| Estimated homesat 750 sq ft average | 1,019 |
| Conversion cost$360/sq ft all-in on 1,419,426 sq ft | $511.0M |
| Gap before grantshortfall against completed value | $61.1M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltBoston's own record of the construction year | 1984 |
| ZoningDowntown Boston | GENERAL AREA |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
33 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 636 ft of exterior wall, and across 48 residential floors the building carries 34,021 ft of it in total, divided among the 1,019 homes this screen estimates.
Its plate is compact at 0.77: close to a square or a circle, the most efficient envelope an office can have and the least generous one for apartments: little perimeter to divide among homes. How window line and plate shape are measured.
At the model’s 750 sq ft average, the plan works out at about 21.2 homes per floor. Its floors are not alike, though: the typical floor's deepest interior point is 62 ft from a facade, while its worst floor reaches 97 ft. The score follows the typical floor, so a podium that could not hold a bedroom does not by itself sink a slim tower above it — but it is there, and it is part of what would have to be drawn around.
Why 669-671 Atlantic Ave scores 63 out of 100
Daylight efficiency 55, Interior depth 44, Scale 100, Finance 83 — each out of 100, then weighted.
Score components for 669-671 Atlantic Ave. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency67% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 55 | 45% | 24.6 |
| Interior depthdeepest interior point 62 ft from a facade, scored from 80 ft down to 40 ft | 44 | 25% | 11.1 |
| Scale1019 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financeremaining gap is 10% of conversion cost, scored from 60% down to 0% | 83 | 15% | 12.5 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 44 out of 100: deepest interior point 62 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1984
Boston records this building as going up in 1984, which puts it in the late-modern stock.
As a rule, typically the hardest to convert: the deepest plates of any era, large central cores, and floor-to-floor heights tight enough that running residential drainage under a ceiling can be the thing that ends a project. That is the era’s general tendency rather than a finding about this building — the model reads an outline and a height, and can see nothing inside — but it is the first thing an architect would want to know, and it colours how much confidence the 67% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 1,419,426 sq ft of converted floor, or $511.0M in total — about $501K for each of the 1,019 homes.
All-in cost per square foot for 669-671 Atlantic Ave: base cost plus the code work a change of use triggers.
| Base conversion cost | $260/sq ft |
|---|---|
| Plumbing risers to every unit | $40/sq ft |
| Operable windows and glazing | $30/sq ft |
| Additional egress stair | $18/sq ft |
| Fire sprinklers (NFPA 13R) | $12/sq ft |
| All-in | $360/sq ft |
That cost is charged across every converted square foot, including the 463,611 sq ft of windowless core, which has to be gutted, re-plumbed and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $442K a home, which for 1,019 homes is $449.9M.
What would have to be true
A $61.1M gap before any grant, $51.1M after the modeled one. The smallest single change that would close it: average unit size 10% down.
The shortfall before any grant is $61.1M. Closing it from the value side means each of the 1,019 homes finishing at $501K rather than the $442K the model assumes — 14% more. Closing it from the cost side means getting all-in cost down from $360 to $317 per square foot.
A modeled RESIDE grant of $10.0M moves that threshold to $492K a home. That is still above the $442K assumed, leaving $51.1M uncovered, which is why the grant does not unlock this one.
Nor do all four levers have to move. For 669-671 Atlantic Ave, one alone would close the gap at:
Single-assumption flip points for 669-671 Atlantic Ave, each holding the other three at their defaults.
| Average unit sizethe binding constraint — the least this building would need | 10% downto 674 sq ft |
|---|---|
| Circulation efficiency | 11% upto 89% |
| Completed value per home | 11% upto $492K |
| Conversion cost per square foot | 14% downto $224/sq ft |
All four are sliders in the survey, where 669-671 Atlantic Ave re-scores against your own numbers.
How it compares in Downtown Boston
669-671 Atlantic Ave ranks 84th of the 96 buildings screened here, against a median score of 89.
Its floor plate is better lit than 10% of them, and shallower than 25% of them at its deepest interior point. On size it is the 3rd largest by estimated homes. The full survey of all 96 buildings ranks and maps every one of them, and the list by address links each to its own page.
Its nearest match in size: 600 Atlantic Ave
The screened building closest to 669-671 Atlantic Ave in converted floor area is 600 Atlantic Ave: 1,242,818 sq ft over 50 stories, against 1,419,426 sq ft over 49 here.
669-671 Atlantic Ave scores 63 to its 83, and with the size held roughly equal most of that shortfall comes from interior depth: 44 out of 100 here, 80 there (deepest interior point 48 ft from a facade, scored from 80 ft down to 40 ft). On the money they part ways: 600 Atlantic Ave pencils only with the modeled RESIDE grant, while 669-671 Atlantic Ave falls short even with the modeled grant. The two stand about 800 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 669-671 Atlantic Ave $10.0M, on the assumption it qualifies. Whether it does, no published dataset can say.
That figure assumes the building meets the Act’s vacant-and-abandoned test, which turns on code-enforcement and receivership records no city publishes.
It does not sit in a 2018 designated Opportunity Zone, so it would not draw that Section 201 priority.
Other buildings screened near 669-671 Atlantic Ave
The 4 closest the screen also covers, from 350 ft away. They are the colored outlines on the plan at the top of this page.
- 175 Federal St20 stories · 83% daylit · 232 estimated homes · scores 87/100 (Strong candidate)about 350 ft away
- 172-180 Federal St7 stories · 91% daylit · 63 estimated homes · scores 88/100 (Strong candidate)about 450 ft away
- 155 Federal St18 stories · 92% daylit · 191 estimated homes · scores 95/100 (Strong candidate)about 520 ft away
- 1 Lincoln St41 stories · 77% daylit · 945 estimated homes · scores 73/100 (Strong candidate)about 600 ft away
A screen, not a feasibility study, from outlines and heights rather than plans: the method and how to correct a figure. If you know this building’s interior, you know what this model cannot see.