North (Dutch) Windmill and Queen Wilhelmina Tulip Garden (pictured below) and South (Murphy) Windmill in Golden Gate Park were built not as replicas, but to be used
- to pump water to irrigate Golden Gate Park in 1902 and 1905. They were only used up to 1913 and then lay dormant and decaying.
The North Windmill restoration was completed in 1981 and there is ongoing work to restore the South (bigger) one. It is still considered the world's largest windmill.
The cap and machinery were sent off to the Netherlands for repair in about 2006. The work on them is completed, but I don't think they are back here yet.
The total project (including a path to join the two) is over $5 mil. It will really be something when all is done to restore them!
October 2011 - the South (Murphy) windmill has been put back together! Much work still needs to be done, but I have included a shot of it here.