Downers Grove GC (Chicago Golf Club I) opened in 1892, but the current routing has little (if anything) to do with the 1892 version. The course was closed from 1897-98 and when it reopened as Belmont Golf Club, some of the land for the original course could no longer be leased. The new management leased/bought adjacent land and opened nine holes, three of them new.
Which ones? Good luck finding a diagram for the 1892 layout. The earliest available is from the early 1900s. Since then (especially in the last 15 years) the course has been renovated. The back-to-back par 3s are gone, for instance. Still fun to be there, though.