Thanks to Jonathan Daniel of Pittsburgh PA for the following information about Louis Steven, the architect of the River Ridge Mansion.
The Architect of River Ridge Mansion
The following is from the "Pittsburgh History & Landmarks Foundation PHLF News" magazine No. 162, March 2002. (http://www.phlf.org/downloads/phlfnews/162_PHLF_NEWS_2002_03.pdf).
Louis Stevens (1880–1961) was born November 4, 1880 in West Brownsville, Washington County, PA,
Stevens established his architectural practice in Pittsburgh in 1906; he retired in 1952. He died August 28, 1961;
he was living at Lynn Run Road, Rector, PA.
To view a map (created by Jonathan Daniel) of other properties designed by Louis Stevens, please select this link: https://mapsengine.google.com/map/edit?hl=en&authuser=0&mid=zBicZmk9VXMY.k_ENjWZlEfM8
The following is from "Pittsburgh of Today, Its Resources and People", Vol. 3, by Frank C. Harper, Copyright 1931.