George Champlin Mason Jr.

Mason's earliest commission is thought to be the Thomas Cushing House in Newport, designed in 1869-70 as an essay in the Stick style.

"[6] With his strong interest in history, it is not surprising that after his father's death, Mason began to pursue commissions that involved historical preservation.

[9] He fought against a proposal to demolish the Old Brick Market, which had been built in 1760, on grounds of the quality of its design by the early American architect Peter Harrison.

In this latter effort, he became one of the first architectural preservationists to argue from primarily aesthetic rather than purely historical grounds, and he has been called the first professional restoration architect in the United States.

In 1895 to 1896, Mason restored the Senate Chamber in Congress Hall in Philadelphia, an initiative launched by The Colonial Dames of America.