This stealth development is already turning East Market Street into a 24/7 neighborhood

If you wade onto the virtual battlefield that is Twitter, it won’t be long before you come across someone talking up the economic urgency of building a Sixers arena between 10th and 11th at Market. The reasoning goes something like this: Market Street’s sidewalks are deserted. The Fashion District Philadelphia mall is on life support. Housing “isn’t viable,” and no one is building anything else. Ergo, the Sixers’ proposal is the last, best hope to “save” Philadelphia’s historic Market Street corridor.

Meanwhile, back on Planet Earth, one of the biggest new developments of the last decade is wrapping up on the 1100 block of Market Street. National Real Estate Advisors has spent more than a billion dollars — yes, billion — to transform a stretch of Philadelphia’s traditional shopping street into the beginnings of a mixed-use neighborhood, which they have dubbed, in a rare act of developer understatement, East Market.

That transformation has been so gradual and so surgical that some Philadelphians may not fully appreciate the extent of National Real Estate’s extraordinary accomplishment.

In just 10 years — the same time frame the Sixers are using for the arena — National has erected two apartment towers, carved a new office building out of an old clothing factory, installed a boutique hotel in a historic 19th-century skyscraper, and brought a supermarket to an area short on such amenities.

Earlier this month, National celebrated the opening of a cheery public plaza at the corner of 12th and Chestnut. That little oasis will serve as the front door for what is shaping up to be a dazzling new flagship for Jefferson Health, the Honickman Center.

East Market isn’t the biggest private development Philadelphia has seen during the last decade; that honor goes to Brandywine Realty Trust’s Schuylkill Yards. In terms of economic value, East Market is twice the size of the Post Bros.’ Piazza Terminal in Northern Liberties and a third bigger than Post’s Washington Avenue development, according to figures supplied by the commercial real estate broker JLL.

Of course, as an architecture critic, I care more about the quality of urban design than the size of the developer’s check. By that measure, East Market is top notch. National could have easily leveled everything on its four-acre site, which runs from Market to Chestnut, between 11th and 12th, and built a sprawling podium, similar to the one that Post is erecting at Broad and Washington. Instead, it has created a new development that feels like a natural part of Philadelphia.

Saving the former Snellenburg’s warehouse and the Stephen Girard Building helped establish continuity with the past. But the decision to put all 480 parking spaces underground, rather than give up precious land for cars, was key. Following a master plan by BLT Architects, National broke the large site into smaller pieces.

That allowed National to thread a network of small streets through the development, reestablishing a lost part of Philadelphia’s intimate grid. It’s no accident that those little streets wend their way toward 13th Street’s restaurant row, which was revitalized by Tony Goldman in the early 2000s. The head of National’s real estate division, Daniel Killinger, got his start with Goldman.

You only have to visit a similar new development in New York, Hudson Yards, to understand the superiority of Philadelphia’s approach. While the Hudson Yards boasts a collection of name-brand architecture, it feels like a walled city because there are no interior streets and no connections to Manhattan’s grid. Philadelphia has always been a city of pretty good architecture and great ensembles. East Market continues that tradition.

East Market’s pedestrian-scaled streets are also good for business. I frequently use them as a shortcut, which means I’ll invariably stop at Federal Donuts for coffee and spend a few minutes checking my messages at a cafe table. Even though the new Jefferson Plaza, designed by Margie Ruddick Landscape and Groundswell Design Group, is meant as a placeholder until the hospital is ready to build another tower, I predict it will become a popular hangout spot in the interim.

When I reviewed the master plan for East Market back in 2014, I called it the “Anti-Gallery.” Today, I’d call it the Anti-Arena.

The Sixers’ urbanism is the antithesis of East Market’s gracious placemaking. Instead of breaking up a large parcel, the Sixers’ plan would form a new superblock by combining their Fashion District site and the land now occupied by the Greyhound Bus Terminal. Instead of reinstating streets, the Sixers would erase a block of Filbert Street. And, after all that, the team still wouldn’t have enough space for an outdoor plaza where crowds can gather before and after games.

To compensate for imposing this superblock on Center City, the Sixers say they plan to include a retail promenade inside the arena. That would effectively replicate the inward-facing conditions that the $420 million Fashion District redesign were meant to eliminate.

For the moment, the Sixers seem to have backed away from an early design concept that would have badly compromised SEPTA’s soaring, light-filled Jefferson Station. At a recent presentation to the Washington Square West Civic Association, Sixers front man David Adelman promised that the station would not be altered by the arena project. But there is something disingenuous about the claim, because building over Filbert Street would create walls that could block some of the light filtering into the underground station.

Even worse is what would happen at street level. Right now, two of the four blocks that meet at the intersection of 11th and Filbert are shadowed by sky bridges — one attached to Reading Terminal, the other at Hilton Garden Inn. Roofing over a third block for the arena would turn that city intersection into a dark void.

Arena advocates say the damage to Philadelphia’s grid would be offset by the economic activity generated on Market Street. Because the westernmost block of the Fashion District would be eliminated to make way for the arena, its owner, Macerich, would be able to concentrate three blocks of shops into the remaining two, thus making the Fashion District more lively and viable. Currently, only 79% of the mall is occupied.

Yet, in study after study, economists have pushed back against the claim that arenas are a catalyst for meaningful economic development.

“A baseball stadium has the economic impact of a midsize department store. A basketball arena has even less,” argues Michael Leeds, a Temple University economics professor who studies sports venues. While the arena might attract new restaurants and bars to Market Street, “you can’t build a local economy on the backs of a sports bar,” Leeds believes.

Unlike East Market, or even the Fashion District, the arena would be inactive much of the time. Leeds doubts that the Sixers would be able to fill the venue more than 80 nights a year. Without a reliable, daily stream of foot traffic, stores and restaurants have trouble surviving. Just look at the 1200 block of Arch Street, directly across from the Pennsylvania Convention Center. After two decades, the only retailer that has located there is a medical marijuana dispensary with papered-over windows.

There is no doubt that Market Street is struggling and that the Fashion District’s future looks poor. But it should be clear by now that housing and offices offer the better path to urban revitalization. East Market is home to roughly 700 people. When Jefferson’s Honickman Center opens next year at 11th and Chestnut, the medical building will attract hundreds of health workers and patients to the area. Every single day.

It was always a mystery why the Fashion District’s owners didn’t include housing during the mall’s renovation. The westernmost block — the Sixers’ site — was built to support two towers. Because the NBA does not allow structures on top of its arenas, the city would lose those building sites if the project went forward.

Philadelphia has been entranced by mega-projects before. In the early 2000s, the city flirted with the idea of putting a Phillies ballpark next to the former Inquirer building at Broad and Callowhill. At the time, the stretch of North Broad between Vine and Spring Garden was nearly deserted. Today, it is lined with apartment buildings. Ditto for South Broad’s Avenue of the Arts, which the city once envisioned as a row of theaters.

If Market Street is going to evolve into a more mixed-use neighborhood, it will need someone to organize and cajole the various property owners. The Department of Planning and Development is the obvious choice and it needs to step in and prepare a master plan. The study should also include the empty zone north of Market Street — between the former Strawbridge’s department store and the Roundhouse — which was leveled more than 70 years ago as part of a misguided urban renewal effort.

There’s actually one use that could work in that spot: a Sixers arena.

A piece of open ground runs from the south side of the Roundhouse to Eighth and Arch. At 4.3 acres, it’s slightly smaller than the Fashion District location. But at least the Sixers wouldn’t face the Herculean task of erecting steel for a new arena while simultaneously keeping the Jefferson Station trains running below.

The site’s other advantage is that it is closer to the I-676 exit and directly across from the publicly owned Parkade garage. The location has good transit access, because it’s right above the PATCO and SEPTA concourse. And because Eighth Street is lined with large institutional buildings, they would buffer Chinatown from the arena. The big downside is that the site is divided up among several owners, including the African American Museum, which is slated to move to Logan Square.

Building an arena at Eighth and Arch wouldn’t be the worst outcome. But I’d still rather see that sprawling block become East Market II.