Complex sentence: The needed fundraising restarted in earnest in 1996--after the real estate depression passed--headed up by Eli Broad and then-mayor Richard Riordan and groundbreaking for the hall was held in December 1999.
Split into simpler sentences: The needed fundraising restarted in earnest in 1996, headed by Eli Broad and then-mayor Richard Riordan. Groundbreaking for the hall was held in December 1999.