Complex sentence: In 1831 the wooden windmill was removed and a new windmill was built on the same spot, which is still one of the town's landmarks today, for it is the only fully functional windmill left in Austria.
Split into simpler sentences: In 1831 the wooden windmill was removed and a new windmill was built on the same spot. This is still one of the town's landmarks today, for it is the only fully functional windmill left in Austria.