[citation needed] The Joseph Sinnott Mansion was listed on the National Register of Historic Places in 1980.

[5] The neighborhood of "Beaupre" in Rosemont was once the 200-acre estate of the same name, built for Alexander Cassatt's son, Robert.

The original French iron gates flank entrances from Conestoga Road and South Ithan Avenue.

[11] Until 1980, the Radnor Township, Delaware County portion of the community was served by Rosemont Elementary School, located in the Garret Hill neighborhood of the town.

It is an all-girl, non-sectarian, day school for PreK-Grade 12 founded by Miss Agnes Irwin and her sister Sofie.