jeah and since then they always built new attractions, changed shows or did something else what could help us to enjoy our time there. And i don´t think they will stop working.
One of my favorite specials on WDW is The History Channel's Modern Marvels - Walt Disney World
It has a ton of info about the construction and early years of both Disneyland and Disneyworld, and some great interviews of Imagineers that were involved in the building of both. It covers the pre-planning and opening of Disneyland all the way through the construction of E:E...I think it was released in 2006.
My husband and I watched it through Netflix, and when we couldn't bear the thought of mailing it back, we searched out a copy at our local Barnes & Noble and bought it!
Also, most of the initial on-site construction was infrastructure improvements. They had to dig canals, build control gates for drainage, build a roadway system, bring higher-capacity electrical service, etc.