Spring training ballparks are great places to take in the national pastime in sunny Arizona. Until recently, these parks have been relatively straightforward to design and construct—most with seating for less than 10,000 fans. Related Links: Salt River Fields At Talking Stick Wins Best Project Award Aces Stadium in Reno, Nev., Is A Community Jewel But a new ballpark under construction in Mesa, Ariz., for the Chicago Cubs, is not only larger than other Arizona spring training facilities—with a 15,000-seat stadium, practice fields, locker rooms, offices and integration of a public park and lake—but it was built within a challenging