Complex sentence: Local architectural firms have major contracts with these and other new proposals, the two biggest (currently under construction) are the Power and Light District, designed by Cordish Company of Baltimore, Maryland, and the 18,500-seat Sprint Center arena.
Split into simpler sentences: Local architectural firms have major contracts with these and other new proposals. The two biggest (currently under construction) are the Power and Light District, designed by Cordish Company of Baltimore, Maryland, and the 18,500-seat Sprint Center arena.