Tilton School is returning an 1860s mansion built for banking magnate Charles Tilton to its original glory. The Tilton, New Hampshire, house’s interior features a mix of styles—Second Empire, Renaissance Revival, Classical Revival, and others—making it “one of New Hampshire’s best eclectic dwellings of the post–Civil War era,” according to its 1982 National Register of Historic Places nomination form.

The private boarding and day school acquired the building at the edge of its campus in the 1960s. Samyn-D’Elia Architects is designing the ongoing renovation, which is expected to cost $5 million provided by both public and private sources. The project began with repairing the roof and stabilizing the Second Empire–style exterior, followed by a full restoration of the first floor, which now houses the school’s United States history program.

Crews rebuilt the central staircase, which had developed a slant. EverGreene Architectural Arts carefully touched up the hand-painted canvas ceiling in the former music room, and general contractor Milestone Engineering & Construction raised a chandelier in the main drawing room about 5 feet for safety reasons. (Legend has it that students swung on it decades ago because it was so low to the ground.) Lighting added during a 1980s renovation was replaced with period-appropriate fixtures, and the team even found some pocket doors buried in the walls. Though the project’s third phase is still underway, students and faculty can use the building. “It’s pretty incredible for those kids,” says Kate Saunders, head of school at Tilton. “Abraham Lincoln was president when this home was built, and now they’re learning U.S. history there.”