Complex sentence: One World Trade Center will be the lead building for the new complex; reaching 100 stories and became the tallest building in New York City on April 30,2012, it is expected to be finished by 2013.
Split into simpler sentences: One World Trade Center will be the lead building for the new complex, reaching more than 100 stories at its completion. It became the tallest building in New York City on April 30,2012, and is expected to be finished by 2013.