Londonderry High School is a public secondary school serving grades 9 through 12 in the town of Londonderry, New Hampshire. The school, located on Mammoth Road (New Hampshire Route 128), is on a 135-acre (0.55 km²) parcel of land in the center of town. The main building is 232,250 sq ft (21,577 m²). and the separate gymnasium takes up an additional 52,000 sq ft (4,800 m²).