Natural Bridge, the Virginia landmark once owned by Thomas Jefferson, and the surrounding 1,500 acres will become state park land by the end of 2015 under an agreement announced Thursday.

The deal will end 240 years of private ownership going all the way back to Jefferson, who purchased it from King George III. The 20-story rock formation, about 45 minutes northwest of Lynchburg, draws 200,000 visitors a year.

Since 1988, Natural Bridge, an adjacent hotel and accompanying attractions have been owned and operated by District real estate investor Angelo Puglisi. Puglisi, 88, agreed to sell the property late last year to the Virginia Conservation Legacy Fund.

The sale was finalized Thursday morning as part of a complicated agreement that involved multiple state agencies and took months to negotiate.

Under the deal, Puglisi agreed to gift the bridge and 188 acres of the property — valued at $21 million — to the fund, said Jim Woltz, president of Woltz & Associates, the Roanoke-based real estate firm that handled the sale. The nonprofit group will pay for the remaining 1,300 acres with a loan from the Virginia Clean Water Revolving Loan Fund, which is overseen by the Virginia Department of Environmental Quality and the Virginia Resources Authority.

Once that loan is paid off, the fund will deed the entire property to the state.

“One of our nation’s most iconic natural landscapes is now protected in perpetuity,” said Joe Elton, interim director of the state Department of Conservation and Recreation.

Natural Bridge once ranked with Niagara Falls as one of the two natural wonders of the New World. A young George Washington is said to have carved his initials into the rock while surveying it for Lord Fairfax.

The bridge was eventually eclipsed by the Grand Canyon and Yellowstone’s geysers but remains enough of a draw that other attractions have sprouted around it, including a wax museum, a safari park and Foamhenge, a plastic foam reproduction of Stonehenge.

For Puglisi, assuring the bridge’s future as a state park is “the fulfillment of a dream,” Woltz said.

The longtime developer did not buy the property to make money but with the aim of keeping it open to the public. His children were not interested in taking over the attraction, Puglisi said, and he spent several years searching for the right buyer. He wanted to find someone who would keep the property intact and not break it into a patchwork of parcels.

In an interview in December, he said that his deepest hope was for the state or federal government to make it a park.

After getting his wish Thursday, Puglisi said in a written statement that he was pleased the agreement “will allow upcoming generations to enjoy it just as I have enjoyed it.”

Puglisi and the new owners have tentatively planned a celebration and ribbon-cutting ceremony in March, Woltz said.

They also will be kicking off a fundraising campaign to help Virginia Conservation Legacy Fund retire the debt. Their goal is to be done by the end of 2015 or sooner.

“The faster it gets paid off,” Woltz said, “the faster it becomes a park.”