The mill is a water powered grist mill in Rock Creek Park. There were at least eight mills along Rock Creek within what is now Washington D.C. Of those eight, only Peirce Mill is still standing. It was built in the 1820s by Isaac Peirce along with a house, barn, and other buildings. It was later owned by a son, Joshua Peirce, and a nephew Peirce Shoemaker. It became part of Rock Creek Park when the park was created in the 1890s.
The family consistently spelled their name "Peirce" (except for some of Isaac Peirce ancestors who went by Pearce). Others often use "Pierce" but not the family. Evidence includes family gravestones, family bible and estate book from Joshua Peirce, and living descendants who still use the old spelling.