Legoland Discovery Center, a chain of children's attractions, plans to open a location at Plymouth Meeting Mall as the mall's owner, Pennsylvania Real Estate Investment Trust , seeks to drum up business at the property. Construction will begin in the summer on the 33,000-square-foot attraction, which will include Lego-block play areas, a cinema, and a "Miniland" with Lego-block replicas of Philadelphia-area buildings, PREIT said Monday.