George Champlin Mason Sr. (1820-1894) was an American architect who built a number of mansions in Newport, Rhode Island, during the Gilded Age.

[1] Mason spent the 1840s trying unsuccessfully to make a living as landscape painter in a Romantic pastoral style derived from the Hudson River School.

[2] Beginning a few years later, he would occasionally write articles for the Providence Journal, the New York Evening Post, and other newspapers, sometimes using the pen names 'Aquidneck' and 'Champlin'.

[2] This was a period when Gilded Age New Yorkers of extreme wealth were building large summer homes in Newport, and Mason became a dominant architect of these residences in the 1860s.

[3] "By-the-Sea" was an Italianate villa with many of the features that would become hallmarks of Mason's style: a formal, squarish building giving an impression of solidity; a modified French mansard roof; a three-bay entrance portico; and extensive use of bracketed trim.

[5] Chepstow includes features such as an interior staircase that pay deliberate homage to American pre-Revolutionary architecture, prefiguring the Colonial Revival period of the 1890s.

Later named Chateau Sunnyside, it still is a private mansion until this day with many of its original features Mason became known for, but it now has an iconic three story Tower that has become synonymous with Newport.

[1][10] Many of Mason's buildings have been demolished to make way for residential subdivisions; however, seven of his residences still stand along the north side of Narragansett Avenue in Newport.