Rensselaer Polytechnic Institute, or RPI, is a private research university located in Troy, New York, with two additional campuses in Hartford and Groton, Connecticut. It was founded in 1824 by Stephen van Rensselaer and Amos Eaton for the "application of science to the common purposes of life" and is the oldest technological university in the English-speaking world. Built on a hillside, RPI's 275-acre campus overlooks the city of Troy and the Hudson River and is a blend of traditional and modern architecture. The institute operates an on‑campus business incubator and the 1,250-acre Rensselaer Technology Park. Numerous American colleges or departments of applied sciences were modeled after Rensselaer. The university is one among a small group of polytechnic universities in the United States which tend to be primarily devoted to the instruction of technical arts and applied sciences.