In 2017, the owner of the Park Square Building borrowed $160 million against it. This past spring, a lender bought the same building back at a foreclosure auction for about $95 million. That is not a typo. A full renovation and one global rate cycle later, the price of one of Back Bay’s biggest buildings landed almost exactly where its mortgage sat two decades ago. The Boston Globe put it plainly: the auction price nearly matched the building’s mortgage from twenty years earlier.
I read that number the way I read a price cut on a listing that has sat too long. The story is not the price. The story is what had to happen first.
A vacant office tower does not become apartments because a tax break made it attractive. It becomes apartments after someone eats the loss on the debt and the price resets to a number where housing finally works. At 31 St. James Ave, the debt got written down from $160 million to about $95 million. Only then did a developer show up with a plan for 490 homes. The conversion did not start with a permit. It started with a write-down.
What actually broke: the tenants left and did not come back
Here is how a full-block Back Bay landmark ends up on the auction block.
The Park Square Building runs an entire block of St. James Ave between Arlington and Berkeley streets, a few hundred feet from the Public Garden. It opened in 1922 and was once the largest building in New England. When Capital Properties refinanced it in 2017 with a $160 million CMBS loan, the building was 96 percent leased. That is a healthy, boring, money-good office building.
Then the tenants left. WeWork took 119,000 square feet and walked away in 2022. Bay State College closed in 2023. Between them, that was more than a third of the building. By June 2024, occupancy had fallen to 42 percent. Today it is about 36 percent leased, and the remaining office tenants are expected to be out within a year.
Capital Properties missed a payment in the fall of 2024 and told the lender it would stop covering the shortfall. The loan went to special servicing. In March 2026, LNR Partners, the special servicer and a subsidiary of Starwood Property Trust, bid about $95 million and took the keys. That bid was roughly $65 million below the loan balance. Someone absorbed that loss. That loss is the whole point.
The number that makes 490 apartments possible is the new one
Now do the developer’s math.
Vanbarton Group, a New York firm making its first move in Boston, filed in August to turn the building into as many as 490 apartments in a project it pegs at up to $410 million. That works out to roughly $840,000 per apartment before a single lease is signed, in a building the developer still has to buy, gut, and rebuild floor by floor.
Numbers like that only pencil when the front end is cheap, and the price has already done the hard part. It reset from a $160 million loan in 2017 to about $95 million at the 2026 auction. Buy the shell near $95 million instead of $160 million, and a $410 million conversion starts to work against Back Bay rents. Vanbarton has floated rents of $6.50 to $7.50 per square foot, which lands around $5,400 a month on an average unit. That is a Back Bay rent, and it is why this address, and not a cheaper building in a cheaper neighborhood, is the one drawing a nine-figure plan.
The write-down is not a footnote to this deal. It is the reason the deal exists.
This is a distress story, not a policy story
Boston has spent two years trying to make conversions happen on purpose, and it is worth being fair about the effort.
In October 2023, the city launched its office-to-residential conversion program. The pitch is genuinely good. A developer gets a 75 percent tax abatement for 29 years, as-of-right zoning downtown, and a streamlined review that has moved some projects through in about six months. On paper it has drawn real interest. By the city’s own December 2025 count, developers had proposed 1,517 homes across 27 downtown buildings. By the middle of 2026, that pipeline had grown to roughly 2,300 units across 36 buildings.
Now look at what has actually been built.
Of those 1,517 proposed homes, 251 were under construction or finished, and exactly one building had opened its doors: 281 Franklin Street, with 15 apartments. Fifteen. Two years into the flagship policy for converting downtown offices, the program had delivered one small building.
I am not knocking the program. The abatement is real money and it will matter over time. But a tax break cannot make an owner accept a loss. It lowers the friction on a conversion. It does not force the decision. What forces the decision is debt. A landlord sitting on a half-empty tower holds on, and refinances, and holds on, right up until the loan comes due and the lender takes the building. Then the price resets, and the conversion that penciled all along on paper suddenly pencils in real life. The single largest office-to-residential conversion ever proposed in Boston did not come out of the incentive program. It came out of a foreclosure.
Boston’s office bust is the fuel, and there is a lot of it
31 St. James is not a one-off. It is the first big one, and the conditions behind it are sitting on top of a large share of downtown.
Boston has the worst office problem of any major market in the country right now, and that is not just my read. MSCI measured commercial property prices across major U.S. markets over the five years ending December 2025 and found that Boston’s central business district posted the steepest decline of any of them. Downtown office values are running roughly 50 percent below their early-2022 peak. The city’s own assessors have caught up to it. The assessed value of Boston’s office buildings fell about 9 percent in a single year, a drop the city has otherwise seen only during the financial crisis and the dot-com bust, and they expect more to come.
That is a citywide balance-sheet problem, and it is also a pipeline. Every repriced tower is a future 31 St. James. Some will refinance and limp along. Some will get handed back to lenders who never wanted to own a Boston office building and will happily sell the shell to whoever has a residential plan. The Park Square deal is the template, and for anyone tracking investment property downtown, the supply story for the next decade is going to run through the lenders, not the press releases.
Not every empty tower can pull this off
A cheap building is necessary, but it is not sufficient. The reason office-to-residential is rare, even with a tax break and a foreclosure discount, is physical.
Apartments need light and air. Every unit wants windows, so a residential floor plate has to be shallow enough that no bedroom sits too far from an exterior wall. A lot of the towers built for open-plan offices and trading floors are deep boxes with a huge windowless core, and you cannot rent a bedroom in the middle of one. You also have to run plumbing to hundreds of new kitchens and bathrooms in a building that was never piped for it. That is why the conversions that actually happen tend to be older, narrower, pre-war buildings, not the 1980s glass boxes.
The Park Square Building is a 1922 structure with a full-block footprint and windows on multiple sides. That shape is a big part of why it drew a $410 million plan while newer, deeper towers a few blocks away sit empty with no taker. So when you hear that Boston has millions of square feet of distressed office space, keep this filter in mind. The price has to reset, and the building has to be convertible in the first place. The overlap of those two is smaller than the vacancy numbers suggest, which is one more reason the new-supply story is narrower and slower than the headlines make it sound.
Why 490 apartments is not new supply anytime soon
This is where I slow people down.
A headline that says 490 apartments reads like 490 apartments are on the way. They are not, at least not soon. Vanbarton filed the plan in August 2026. The remaining office tenants are not even out until sometime in 2027. Under the city program, the developer has to pull a full building permit and start construction by the end of 2027 just to keep the abatement. Then someone has to gut and rebuild eleven floors of a 1922 building, run new plumbing and electrical to 490 kitchens and bathrooms, and lease the whole thing up.
For scale, 281 Franklin Street was 15 units in a six-story building, and it still took about a year and a half from approval to the first resident moving in. The mid-size conversions that started downtown in 2025 are delivering in 2027 and 2028. A 490-unit conversion of a full-block tower is a different animal. Realistically, the first tenant at 31 St. James is a 2029 story, and 2030 would not surprise me. So if you are watching this deal, watch the calendar, not the unit count.
What it means if you are buying or renting near the Public Garden
For renters and buyers watching Back Bay, this is real competition, eventually.
Back Bay does not add housing. The blocks are built out, the buildings are protected, and new supply of any size is rare. Dropping up to 490 apartments into that market, a few hundred feet from the Public Garden, is a genuine shift at the top of the Back Bay luxury market. About 20 percent of the units would be income-restricted, which is a real entry point in a neighborhood that almost never offers one. The rest would compete at the high end of the Back Bay rental pool.
The catch is the timeline from the last section. If you are renting in Back Bay in 2026 or 2027, this project does nothing for you. If you expect to be in the market around 2029 or 2030, it belongs on your radar, because a big new building leasing up all at once tends to hand renters the one thing Back Bay almost never gives them, which is choice and a little room to negotiate. For buyers, note the word apartments. This is a rental project, not condos. It is not adding for-sale inventory, so it does not change what you are bidding against on a Back Bay condo today.
If you already own a Back Bay condo
If you own a condo in Back Bay or the blocks around it, I would file this under watch, not worry.
Nothing about this project touches your value in the near term. It is rental, so it does not compete with your unit if you sell in the next few years. And even as future rental competition, it is years from leasing. The honest read is that you have time. The thing I would actually watch is whether the project breaks ground on schedule and whether it turns out to be the first of several. One converted tower is an event. Five converted towers over a decade would slowly change the supply picture in the priciest, tightest part of the city, and that is the scenario worth tracking if you are deciding whether to hold or sell a Back Bay condo as a long-term investment.
If you want to know where your specific building sits in all of this, that is exactly the kind of thing I work through with clients. A quick read on your home’s current value is a good starting point, and we can talk through the neighborhood supply picture from there.
What I am telling clients
Here is the short version I give people who ask.
The office-to-housing story in Boston is not really a policy story yet, whatever the announcements say. Two years of incentives produced one finished building. One foreclosure produced a plan for 490 homes. The lesson is that distress, not tax policy, is what actually moves an empty office tower into the housing column, and Boston has more distress coming than any other office market in the country. That is the supply engine to watch.
For buyers and investors, the move is patience plus attention. The units are real but slow. The pattern is real and repeatable. Watch which towers get handed back to lenders, because those are the ones that convert. For Back Bay condo owners, you have runway before any of this becomes competition.
If you are trying to figure out what a wave of downtown conversions means for a specific building, a specific block, or a purchase you are weighing, reach out. I would rather walk you through the real timeline than let a headline make the decision for you.
