Complex sentence: In the mid- to late 2000s there was a building boom, as more high-rise buildings were constructed, however there is a height restriction on the isthmus, to protect views of the Wisconsin State Capitol.
Split into simpler sentences: In the mid- to late 2000s there was a building boom and more high-rise buildings were constructed. There is a height restriction on the isthmus in order to protect views of the Wisconsin State Capitol.