Complex sentence: By late 2005, the restoration was complete and in December, Verizon, announced it would move its headquarters from midtown Manhattan into the downtown building which had space for 1,500 employees.
Split into simpler sentences: By late 2005, the restoration was complete. In December 2005, Verizon, at the time headquartered in midtown Manhattan, announced it would move its headquarters downtown into the building, with space for 1,500 employees.