The Rensselaer School began its existence in a single building known as the Old Bank Place on the northwest corner of River and Middleburgh Streets. The structure was erected in 1801 at a cost of $11,000 to house Troy's first bank, the Farmer's Bank. Amos Eaton acquired the building on a lease in 1821. The Rensselaer School opened at the Old Bank Place on January 5, 1825 and remained there until 1834. The building housed laboratories with scientific instruments and specimens, an observatory, a library, lecture rooms and living quarters for the students and the Eaton family. The school leased the Van der Heyden Mansion from 1834-1841 then returned to the Old Bank Place in 1841. An 1841 catalog describes the site as "airy, healthy, and rural, surrounded by fields, hills and groves." Rensselaer remained at the Old Bank Place until 1844.