The largest of Mercersburg's early houses was built for Robert Parker, a Revolutionary War veteran whose appointment as collector of excise for Franklin County brought him to Mercersburg, then on the principal east–west road between Pittsburgh and Baltimore. Built of local limestone with jack arches over the windows flanking a central transomed door, his house could have been built anywhere from Lancaster to the mountains. With handsome carved mantels and turned balusters for the stair it epitomized the contemporary taste as Georgian gave way to the Federal style.