Amid high-rises and office buildings, modern architecture and refurbished condominiums, the quaint, Colonial-style house that sits on Washington Square stands out in more ways than one.

At just three stories and 3,800 square feet, the Dilworth House on South Sixth Street represents another time. With a pitched roof and white trim, the red brick house appears as if it's withstood change for decades as the city has revitalized around it.

Yet that's not the most surprising thing about the Dilworth House: While Washington Square has become some of Philadelphia's premier real estate, the house has sat vacant for more than a decade. Paint on its classic white shutters has flaked and chipped. Boards have replaced windows. And in the backyard, grass, cut only sporadically, has grown tall. Last month, the city issued multiple violations against the owner for the lack of upkeep.

It's an unexpected fate for the house, which is regarded as historic not for its age but for its location and significance. When Society Hill was rundown in the mid-20th century, Mayor Richardson Dilworth signified his commitment to improving the area by building the house  in 1957 to live there.

Over the last 16 years, big plans for the house have been made — and fought. When developer John Turchi Jr. and his wife purchased the house in 2001 for $1.75 million, they wanted to renovate and move in. Then, the plan shifted to demolition, and then partial demolition, to make way for a 16-story condo tower. A nearly decade-long legal battle involving Turchi, the city, and residents ensued, until finally, in 2015, the Commonwealth Court upheld Turchi's plan: The Dilworth House's rear and side wings could be demolished, and the condo tower was approved.

Yet today, no construction, no tower. Two years have passed since Turchi won approval, so why hasn't anyone followed through?

According to Turchi's lawyer, Philip S. Rosenzweig, Turchi, now 75, has "quietly" marketed the property and "was actively looking to see if there was a developer who would be willing to acquire the site and build it."

"At the moment, there is no transaction happening, but the opportunity exists for one of Philadelphia's preeminent developers to acquire the site," Rosenzweig said. "Mr. Turchi is committed to the project. He has no intention of relinquishing."

But tackling Turchi's project will be no easy feat, according to developers, and city officials familiar with the site. Long-standing community tensions still permeate, and logistically, the experts said, construction would be difficult. Zoning variances are needed. Parking is problematic. The lot measures nearly 9,000 square feet — but the house takes up part of it — meaning a tower would be confined by not just height, but also width and depth.

Yet the site still has appeal. Society Hill is now considered the wealthiest zip code in Philadelphia, and Washington Square is just steps from what is considered the next development area — Independence Mall. The Dilworth parcel is the last piece of land available for new construction on Washington Square, making it valuable, experts say, and residential development would likely draw strong demand from potential tenants.

But with the property's limitations, a developer would need to be assured of a profit — condos, if still pursued by a new owner, are generally considered to be one of the riskiest real estate investments. Plus, according to a Historical Commission spokesman, the property would be subject to at least six zoning overlays that could limit its height or parking, for example. And, he added, it is not clear whether the commission's prior approval would transfer to a new project.

"It's a small lot — it's like trying to stuff five pounds of cream cheese into a one pound bag," said Councilman Allan Domb, known as the "Condo King" as a result of his real estate brokerage. "A developer would be buying into an environment where there has been a fight for 10 years and where residents are concerned about the impact on this small-sized land."

"I'm not saying it can't be done," Domb said, "but I'd love to see the developer sit down with neighbors and see what works for everyone."

Since Turchi began shopping it, the site has caught the eye of some of Philadelphia's top developers. Tom Scannapieco — whose $17.85 million penthouse at 500 Walnut, right around the corner, broke the record for the most expensive residential sale — said he explored the possibility of buying the Dilworth site six to nine months ago, but walked away.

"This is one of the most contentious pieces of real estate in the city," Scannapieco said. "… It's frankly a heavy lift with an unknown ending."

Other developers declined to comment on the record.

When Turchi's demolition and condo plan emerged in 2004, it rattled the neighborhood. Society Hill was declared a historic district in 1999, and the Dilworth House was classified as "significant." Removing that classification, as Turchi sought to do, would erase a property that residents believed was crucial to Philadelphia's history.

But as Turchi saw it, the house was not historic. "It's in the wrong place and it represents the wrong time," he told the Inquirer in 2005. He did not return calls for this story.

After years of back and forth, finally, in 2007, the Historical Commission sided with Turchi: He could demolish the back half of the home, if the front facade was preserved. Behind it, a 16-story tower, designed by architect Robert Venturi, could rise.

Quickly, neighborhood residents appealed that decision, arguing that none of the house should be demolished, and the city's Board of Licenses and Inspections sided with them. Turchi fought back, and appeals continued until 2015, when the Commonwealth Court upheld the 2007 Historical Commission's decision. By then, Washington Square and the real estate market were entirely different places.

In the mid-2000s, the condo market was heating up locally, and developers were piling on. Some projects, such as the Lippincott Condominiums next door,  the Ayer condos across the square, and Toll Brothers' Naval Square in South Philadelphia, were successfully completed. Many were derailed by the recession.

The condo market has since regained steam, something largely attributed to Carl Dranoff's and Scannapieco's newer luxury condo developments.  Today, developers have also been concentrating efforts around Independence Mall — with multiple projects underway, including 500 Walnut, Keystone Property Group's Curtis building renovations, and MRP Realty's redevelopment of the Bourse building.

"People are saying that this is the new frontier," said Paul Levy, president and CEO of the Center City District. "… All around this [Dilworth House] site, there is a tremendous amount of new activity."

For now, the only activity at the Dilworth House was the arrival of contractors in late July to paint the exterior. The Department of Licenses and Inspections had issued Turchi nearly a dozen violations, from failing to comply with historic property maintenance to allowing overgrown weeds.

According to Paul Boni, the chair of the zoning and historic preservation committee for the Society Hill Civic Association, which fought Turchi in court, neighbors are still keeping a careful watch.

"We are well-prepared to make sure the law is enforced," Boni said. "This is the Dilworth House. It has importance in the … evolution of our neighborhood."

"Has [Turchi] approached us with a proposal and has anyone else approached us? The answer is no," he said. "Developers have long time horizons;  the property isn't going anywhere."