At the crest of a windswept bluff overlooking the confluence of Crosswicks Creek and the Delaware River in Bordentown, Joseph Bonaparte — oldest brother of Napoleon, former King of Spain, self-exiled diplomat, and Philadelphia resident — built a country estate called Point Breeze that was a wonder of early 19th-century America.

Only the White House was larger than Bonaparte’s first residence on Point Breeze, where his collections of paintings, books, and birds were also among the best and biggest in the young United States. Swan boats glided on the half-mile-long lake he created. Tulip poplars rose skyward from a carefully curated “picturesque” landscape that he designed and whose style he helped popularize. And from the dock, a network of tunnels enabled horse-drawn carriages to deliver provisions and luxury goods, shipped upriver from Philadelphia, to Bonaparte’s sprawling array of homes and gardens.

The estate’s grand buildings are long gone — indeed, the circa 1820 gardener’s house is the only extant structure that still stands. But the 55-acre heart of this extraordinary piece of Burlington County real estate now belongs to the public. The $4.6 million purchase by the New Jersey Department of Environmental Protection, the City of Bordentown, and the nonprofit D & R Greenway Land Trust was finalized Dec. 18 with Divine Word Missionaries, the Catholic order that had owned the site since 1941.

“For Bordentown, this is a once-in-a-lifetime event,” said Mayor James E. Lynch, who was born and raised in the historic one-square-mile city of 3,800 that, like Philadelphia, was established in 1682. Bordentown’s $1.6 million piece of the purchase yields the city a cluster of well-maintained, mid-20th-century buildings erected over the years by Divine Word that will be converted into a new City Hall, police department headquarters, and community center.

The D&R Greenway Land Trust now owns and will restore the gardener’s house, and also plans to replicate the vegetable gardens that flourished while Bonaparte lived at Point Breeze on and off between 1816 and 1839.

The other 50 acres of fields, dense woods, carriage trails, and steep embankments will be part of New Jersey’s state park system; eventually, there will be interpretative signs, audio tours, and walking trails offering glimpses of tunnel entrances, remnants of bridges (there were once seven), sandstone stairways, and views of the water.

“I can’t begin to tell you how proud I am to turn this over to our residents, and to future generations,” said Lynch. “This would never have happened if the stars hadn’t lined up.”

Land Trust president Linda J. Mead was just as effusive about the historic tract, which is the southern gateway to the Abbott Marshlands between Bordentown and Trenton. “This wetlands area was the most important Native American settlement east of the Mississippi,” she said. Once it’s open to the public as a park, Point Breeze “will draw visitors who can then discover the Delaware River watershed and the region’s broader hiking and water-trail network.”

» READ MORE: In 1807, N.J. women and free people of color lost the right to vote. The Museum of the American Revolution explores why.

In recent years, developers had eyed the Divine Word property as a potential site for construction of a mega-warehouse like those springing up elsewhere along the NJ Turnpike and I-295 corridor in Central and South Jersey. But a devoted band of local historians, preservationists, and environmentalists were determined that Point Breeze not become the location of yet another distribution center.

“It’s a unique site,” said Doug Kiovsky, vice president of the Bordentown Historical Society, adding that “not many places in this country can claim that a king” once resided there.

“It’s also the city’s last large tract of undeveloped land,” Kiovsky said. “To have it become a warehouse [site] would have been a travesty. To have it become something for people to enjoy is magnificent.”

One of the site’s longtime champions is Peter Tucci. A Philadelphia lawyer and New Hope resident, he began collecting Joseph Bonaparte letters and other materials in the 1990s, while serving as president of the Philadelphia Chapter of the French-American Chamber of Commerce. Tucci became fascinated with Point Breeze and helped organize a symposium there in 2008 that included Pierre Vimont, then the French ambassador to the U.S. The event drew about 300 people and generated interest in the future of the site.

“You can understand why a former king would choose this for his home,” said Tucci, who in 2005 was named a Chevalier (Knight) of the French Legion of Honor — which was established by Napoleon Bonaparte.

“Joseph Bonaparte spent what today would be about $50 million to build his first house on Point Breeze, Tucci added.

Joseph Bonaparte and other family members emigrated to the United States after 1815 when Napoleon, who had earlier declared himself emperor of France, abdicated. Joseph was wealthy, well-educated, and well-acquainted with fellow French emigres such as Philadelphia banker Stephen Girard.

At Point Breeze, he entertained Girard and other luminaries like Francis Hopkinson, who signed the Declaration of Independence, the naturalist John James Audubon, and Thomas Paine. With its library — saved from an 1820 fire by local volunteers who also rescued the paintings — and its art collection, Point Breeze nurtured the new nation’s culture. And his landscape design at what was originally an 1,800-acre estate also was influential on future public spaces.

» READ MORE: Gated off and guarded by dogs, Lynnewood Hall is still a mystery. Except to YouTube.

“Landscape design in the 18th century had been formal and geometric, but a more natural, picturesque [approach] started to make inroads in the beginning of the 19th century,” said Monmouth University professor Richard Veit. “Point Breeze was a big estate on America’s highway between New York and Philadelphia, and everyone saw it and commented on it. Joseph Bonaparte was a pioneer.”

Veit also directed a three-year excavation at Point Breeze that yielded 23,000 artifacts — a final report is pending — and said the property is among the most archaeologically significant in the state.

“It’s fantastic that a number of folks came together and formed this great alliance that allowed them to think outside the box and save one of the region’s great treasures,” he said.

Tucci is particularly pleased to see Point Breeze preserved because he sees it as having “not only regional, but national and international significance.”

After all, Joseph Bonaparte helped negotiate the Treaty of Mortefontaine; signed at his French estate in 1800, it cemented the enduring alliance between the United States and France.

The Rev. Martin H. Padavani, 89, a priest with the Society of the Divine Word who until the sale had lived at Point Breeze for 60 years, said he was sad to leave but glad to know the grounds “where I must have planted 50 trees” will be preserved. “We always said that if we were ever to leave this beautiful place, it should be passed on to the people of New Jersey.”