Now, the uncovered ruins of the steel mill and other 18th- and 19th-century mills and buildings - built atop one another like the layers of a cake - will be reburied by spring for about $400,000.
The cost of turning the site into a publicly accessible park - estimated to be in the millions - is unaffordable when New Jersey is struggling to maintain parks it already has, state officials said.
So the State Capitol Joint Management Commission voted last month in favor of Lt. Gov. Kimberly Guadagno's order to fill in the site and protect the ruins until better economic times, when the state can revisit plans for a park.
"The No. 1 reason is economics," Irene Kropp, deputy commissioner of the state Department of Environmental Protection, said last week. "Let's focus the money on current parks, and let's preserve [the Petty's Run site] properly so we can open it again when we have money to build a really cool interpretative center with staff."
That decision, though, has drawn the ire of historians and Trenton boosters, including business owners and civic leaders. They hope to meet soon with Guadagno and persuade her to keep the site open as a way of drawing more visitors.
"We're looking to enhance the business climate, and tourism is one area we've identified as a key opportunity for doing that," said real estate developer David Henderson, chairman of the nonprofit Trenton Downtown Association. "It makes more sense to stabilize the site, fence it in, and provide public access to get as much economic draw as we can."
"If it is viewable in a minimal way, it will draw visitors and dollars and generate revenue for the state. We understand the desire not to waste money, but this can add another boost to the economy."
Ron Emrich, executive director of Preservation New Jersey, a nonprofit dedicated to protecting the state's historic resources, communities, and landscapes, asked why there was such a rush to bury the site and not explore other possibilities.
"This is a tremendous lost opportunity," Emrich said, pointing out the public interest generated by Philadelphia's excavation of the President's House site, where the slaveholding George Washington and the antislavery John Adams conducted their presidencies in the 1790s. "If we cover over [the Trenton site], the likelihood of ever opening it again seems highly unlikely."
As an active dig, the site "has great potential for scholarly work and archaeology" as well as tourism, said Cate Litvack, executive director of the Crossroads of the American Revolution Association, a nonprofit offering a forum for new initiatives on education, historical interpretation, site use, and heritage tourism.
"It's incredibly fascinating to have discovered so many layers of Trenton's history," she said. "Anything that encourages more heritage tourism in New Jersey, I'm in favor of."
Lawmakers - including Assembly members Bonnie Watson Coleman and Reed Gusciora, both Trenton Democrats - have joined the voices supporting development of the site.
"Burying this archaeological dig at the Statehouse is a blow to our heritage and efforts to recognize it and promote it as a tourist attraction and economic-development tool," Coleman said, adding that it would be "of great interest to schoolchildren and visitors to Trenton. Instead, it will be forsaken and buried for no logical reason."
Archaeological work began at the Petty's Run site to prepare it as a focal point of what the Corzine administration had planned as Capitol State Park.
The proposed $87 million four-phase project was to extend from the Statehouse grounds to the Delaware River. The construction would have cut under the heavily traveled, four-lane Route 29, which blocks access to the river. It also would have created a waterfront park.
But the plan, including the efforts to turn the dig into a historic attraction, stalled with the state's financial crunch.
Archaeologists cataloged their finds, including pottery and furnace-related metals. The mill operated from 1745 to the 1780s, Burrow said. The remains of an iron forge dating to 1731 also was found, along with a cotton mill and paper mill from the 19th century.
Rowhouses were built over the site in the 1870s and lasted until early 1910, when they were knocked down to make a park.
But it was the steel mill that generated the most interest among historians, some as far away as Britain, Burrow said.
"This is the first one excavated in North America," Burrow said. "There weren't many built in the colonial period, and there's only one where you can go and see what it looked like. None of the others survived or have been archaeologically excavated."
Turning that history into a tourist attraction, though, will have to wait, state officials said.
"It sounds crazy, but there is a proper way to preserve the site by filling it in," said Larry Ragonese, a DEP spokesman. "Creating a new park when we're struggling to keep existing parks open doesn't make sense.
"If we take what we can from the site, showcase it, and seal [the location], we have done a positive thing for the current time and the future."
Petty's Run "is a great idea down the road," Ragonese added. "Right now, it can't happen."
Contact staff writer Edward Colimore at 856-779-3833 or email@example.com.