Complex sentence: Civil engineering works started in late 2006 with the removal of the former underground garage of the Zürich Tower, while the groundbreaking for the development of OpernTurm took place on 22 January 2007.
Split into simpler sentences: Civil engineering works started in late 2006 with the removal of the former underground garage of the Zürich Tower. The groundbreaking for the development of OpernTurm took place on 22 January 2007.