2025 Diana Stakes: Rich History & Saratoga’s Turf Showcase   The Diana Stakes, inaugurated in 1939, is turf racing royalty. Held at Saratoga Race Course, this Grade I stakes for fillies and mares (age 3+) runs over 1⅛ miles with a $500,000 purse. As horse racing betting ramps up for this weekend’s card, savvy fans are checking horse racing odds and preparing their strategies in their racebook accounts.