Complex sentence: Most of the inaugural balls for the 2005 Presidential Inauguration of George W. Bush were held at the convention center, and six of the 10 official balls of the 2009 Presidential Inauguration of Barack Obama took place there, including the first-ever Neighborhood Ball.
Split into simpler sentences: Most of the inaugural balls for the 2005 Presidential Inauguration of George W. Bush were held at the convention center. Six of the 10 official balls of the 2009 Presidential Inauguration of Barack Obama took place there, including the first-ever Neighborhood Ball.