jno...I visited a similar house to the Ennis place, in LA, about 16 years ago :::
https://en.wikipedia.org/wiki/Hollyhock_House
It was built in 1919, but looks much more recent. Its built out of preformed concrete blocks, in the same way as the Ennis House ( which was used as filming location in "Blade Runner" )
The difficulty with these concrete block houses is that the material reacts rather badly with the pollution you find in LA. This, of course, wasn't an issue in 1919 ! The Ennis House was also badly damaged by an earthquake in 1994.
The Hollyhock House is easy to visit and well worth it if you are in the area again. Its part of a large art gallery complex. The new tube network in LA stops right beside the house, so it couldn't be easier to get to.
While I am on the subject of FLW, not all his houses were built for very wealthy people. Here are two more that I have visited :::
http://architecture.about.com/od/franklloydwright/ss/flwzimmerman.htm#step1
https://www.google.co.uk/search?q=Kentuck+knob&rls=com.microsoft:en-GB:%7Breferrer:source?%7D&rlz=1I7ADFA_en&tbm=isch&tbo=u&source=univ&sa=X&ved=0CEEQsARqFQoTCPqRjMX6-MYCFQVdFAodLTMNFw&biw=1024&bih=726
Again, the interiors are beautiful....lots of natural stone and wood. Also note that all the furniture, carpets, rugs and seating, etc was designed by Wright as well !
If anybody is interested, Falling Water and Kentuck Knob are quite close together, so its quite easy to visit both in the same day.