This is not really a Netherlands festival. It is, in fact, from the south of France where they actually grow citrus. These pictures are from the French Festival Citrusov.
It is amazing to see that oranges can be used to build windmills, castle, houses and so on. This shows that everything is possible to happen with creative minds and ideas.
The whole city comes alive with the bright orange colour that you can see everywhere. It should be very fun to visit Netherlands during the Orange Festival.