St. Denis is an unincorporated community in Baltimore County in Central Maryland, United States, located in Arbutus, south of Baltimore.

Saint Denis, Maryland
unincorporated community
The Relay Hotel, once located at the Thomas Viaduct on Railroad Avenue
Coordinates: 39°13′22″N 76°42′17″W / 39.22278°N 76.70472°W / 39.22278; -76.70472
Country	United States
State	Maryland
County	Baltimore
Founded by	Dennis Smith[1]
Time zone	Eastern

It is located on the CSX main line between Halethorpe and Relay (the latter being the site of the Thomas Viaduct), and is best known as a stop on the MARC commuter rail (on the Camden line). In former years, a station building stood here similar to that in Germantown, but all that remains are the platforms. That station, built in 1891, was destroyed by an arson fire in 1976. The Maryland Transit Administration considered discontinuing this stop in 2006 but was prevented from doing so by legislation in the Maryland General Assembly.

The Halethorpe MARC station is on a different line than the St. Denis station, as St. Denis is on the former Baltimore and Ohio Railroad, and Halethorpe on the former Pennsylvania Railroad.