|Location||Lake Forest, Illinois
|Tournaments hosted||1906 U.S. Open|
|Designed by||Charles B. Macdonald
Herbert J. Tweedie
redesign by Tom Doak
|Length||6,645 yd (6,076 m)|
The course features 6,645 yards of golf from the longest tees for a par of 71. The course has a rating is 71.9 and it has a slope rating of 127 on Chicago (bent) grass. Charles B. Macdonald designed the first 9 holes in 1895. The second 9 holes were designed in 1898 by Herbert J. Tweedie, James Foulis and Robert Foulis.  The course was subsequently redesigned by Tom Doak.
1906 U.S. Open
Tom Doak redesign
The club has panoramic views of the property at almost all points, and the Doak redesign keeps the integrity of some holes intact. The fescue and multi-tiered putting surfaces compensate for length on this gem. The name "Onwentsia" may have been inspired by the Illini name for the tuliptree, which grows in well-watered Illinois ecosystems.
- "Chicago Aerials: H.J.Tweedie From Hoylake to Chicago". golfclubatlas.com. Retrieved 20 May 2015.
- Brenner, Morgan G. (2009). The Majors of Golf: Complete Results of the Open, the U.S. Open, the PGA Championship and the Masters, 1860-2008. 1. McFarland. ISBN 978-0-7864-3360-5.