Just over the footbridge, behind those dense deciduous trees, lies the interior of Roosevelt Island.

Centuries before that bully memorial to our 26th president was begun in the 1930s, the 88-acre island once known as Analostan was glimpsed by Captain John Smith and inhabited by Native Americans.

But this same turf within spitting distance of the nation’s capital also plays an intriguing role in Arlington history. I heard details last month when a National Park Service cultural resources specialist presented to the Arlington Historical Society at Central Library.

Bradley Krueger laid out the travails of John Mason (son of the Gunston Hall owner who conceived the Bill of Rights), who built a summer mansion there beginning in 1806.

Mason owned sizable land, Kreuger said, stretching from modern Arlington Cemetery to Chain Bridge and west up to Lee Highway. (That would include the mid-19th century home Dawson Terrace and a mill on Spout Run.)

A banker, Mason had a main residence in Georgetown, and enjoyed ferry service to the island begun decades earlier. But a fire broke out at the in-progress home. The event is recorded in a letter from President Thomas Jefferson: “One wing was burnt down and the middle nearly so. They saved their furniture. Suspicions arising that it was done by one of his house servants who wished the family to go back to Georgetown, he was arrested and on his way to prison with the constable, he jumped out of the boat and drowned himself. I understand the family will continue through the summer in the remaining wing.”

By 1807, the island had a causeway, Kreuger said, and that bridge and ferry were likely used in 1814 by President Madison when he was fleeing the British to Falls Church and McLean.

Mason planted gardens and orchards. He owned nine slaves (according to his 1856 will). He competed in sheep shearing against neighbor George Washington Parke Custis, who was building Arlington House around the same time. Both enjoyed views of Georgetown and may have used the same British architect, George Hadfield.

Keeping the island’s south side private and the north side public, Mason’s British gardener achieved what one period travel guide writer called “the most enchanting spot I’ve ever beheld.” According to Gunston Hall curators, Mason Island hosted James Monroe, and Louis Phillipe, Duc d’Orleans, later King of France.

But in 1833, Mason had fallen on hard times and had to sell. The public reason: mosquitos. He departed to Fairfax to raise sheep. Mason’s Island was bought by the Carter family and then by D.C. Postmaster William Bradley, who created a retreat where the wealthy enjoyed dancing, feasts and jousting.

During the Civil War, “colored” Union troops drilled there, secluded from local whites, Krueger said. Troops would also train there in the Spanish American War and World War II. In the 1880s the island became the Columbia Athletic Club (a photo of the house survives from 1890).

In 1913, the Washington Gas Light Co. bought the island. The Ballston Boy Scouts camped there.

In 1931, it was sold to the Roosevelt Memorial Association. The Civilian Conservation Corps was brought in to restore the island’s rare plants, and archaeologists excavated the Mason home ruins.

That statue of Roosevelt wasn’t completed until 1967. It is the area’s largest, hidden from all but island visitors.

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Our bright future? The accounting and consulting firm Grant Thornton LLP gave Arlington a vote of confidence last February when it celebrated the move of its Washington-area offices from Alexandria to Rosslyn.

After hosting county officials at a ribbon-cutting party in its high-rise suite, executives confided in me a secret factor in their selection of the new location.

A computer mapping of the home addresses of Grant Thornton’s local employees and clients showed that the bulk were bunched around Metro’s path along the Rosslyn-Ballston corridor. Many transportation hours saved.