Alexander Johnston Hall is a historic building located on the corner of Somerset Street and College Avenue, New Brunswick in Middlesex County, New Jersey and is the second oldest building on the campus of Rutgers University.

It was built in 1830 to handle the expansion of the Rutgers Preparatory School and the two literary societies, Philoclean and Peithessophian.

[4] Designed by local architect and builder Nicholas Wyckoff in 1830, Alexander Johnston Hall served as the home of the Rutgers College Grammar School, later known as the Rutgers Preparatory School.

[4] In 1870, the Rutgers College trustees hired architect Henry Janeway Hardenbergh (1847–1918) to design a two-story addition for the building.

In 1964, the university renamed the building to honor 1870 graduate, Alexander Johnston, a historian and classics instructor at the school.