Harriton House, originally known as Bryn Mawr, is a historic house on Pennsylvania's Main Line, most famously the residence of Charles Thomson, the secretary of the Continental Congress. It was originally built in 1704 by Rowland Ellis, a Welsh Quaker, and was called Bryn Mawr, meaning high hill. The modern town of Bryn Mawr is named after the house, and the National Register of Historic Places has it listed under the original name.