Pennsylvania Hall, also called Old Dorm, is the central administration building at Gettysburg College and the college's oldest building. John Cresson Trautwine designed it in 1835, and it was built in 1838 in a temple style with four columns in the portico. At first it held students' rooms, offices and classrooms.
When the battle came in July 1863, it was the largest building in town. Union signal officers used its cupola on June 30, and on July 1 a professor led officers up to look out over the area. Soldiers of both armies were treated in the building, nearly 700 of them, until about July 29.
Classes started again on September 24, 1863. The hall was renovated in 1869 and 1870, 1889, and 1928. It is still used for the college's opening and graduation traditions.