Rensselaer is located on the Hudson River, directly opposite of Albany. The area was part of the Rensselaerwyck manor. Rensselaer was originally called Greenbush. and Rensselaer’s name came from Kiliaen Van Rensselaer, the original landowner of the region in New Netherland.The City of Rensselaer is located on the west border of Rensselaer county.

The town of Greenbush which was incorporated in 1815, changed to Rensselaer in 1897 when Greenbush was chartered as a city officially. In 1902, the limits of the city were extended by the annexation of Bath and the western part of East Grennbush.

There is a major Amtrak station located in Rensselaer. The track also serves Albany and Troy and as many as 6 trains run from Albany-Rensselaer to New yorkl City every weekday morning.

Rensselaer isĀ  also the home to historic Fort Crailo.