Mastro Auctions to conduct world’s most concentrated auction of high-end Sports memorabilia, many items never before publicly offered, including Griffey’s 600 home run ball; portion of event to benefit the Derrek Lee 1st Touch Foundation. Mastro Auctions, the world’s leading Sports and Americana auction house, has announced that it will bring its second Live Sports Auction to the Second City on Friday, August 1st at 8:30 p.m. at the ESPN Zone in Chicago. The historic auction will include more than 90 items of the world’s most coveted pieces of current and vintage sports memorabilia including several that have never before been available to the public. Preview is now available by clicking here.