M*A*S*H was filmed in two locations. Stage 9 at Fox Studios and the Fox Ranch (now Malibu Creek State Park). Much of the set is in storage, but The Swamp, O.R., and iconic sign post sets were donated to the Smithsonian. They were on display in the mid-1980s, but have been since placed in storage.
Although you may not be able to see the M*A*S*H set today, you can visit Malibu Creek State Park. This is where all outdoor scenes were filmed for the series and the movie. A short two miles hike from the visitors’ center, the M*A*S*H site has been updated to include a replica of the sign post, historic markers, and rope outlines of the original buildings. YouTube user JetCityFlight visited the M*A*S*H site over the summer and posted a video tour of the site. Enjoy!