#12. The Gathering Place, Tulsa, Oklahoma: When the philanthropist George B. Kaiser spearheaded the creation of this $465 million green space on Tulsa’s waterfront, he hoped to help unite the city, which has struggled with inequality. The 66-acre park, which is open to the public for free, includes playgrounds, gardens, a skate park, a BMX track, a concert venue and a number of restaurants. (Image: Stock)