Millbrook Square features an outdoor swimming pool that is open weather permitting from May 1 through Labor Day. Millbrook Pool is open to the Washington University community permitting summer barbecues and pool parties for students and faculty. There is also a playground for the adjacent Nursery School
The name Millbrook comes from the combinations of the last names of David Millar and Robert Brookings. David Millar was a Washington University graduate and brother in the Gamma Omicron Chapter of the Sigma Nu Fraternity. He was the mayor of University City from 1933 to 1937, and a prominent Saint Louis Lawyer. Robert Brookings was a Saint Louis businessman and president of the Washington University Board of Directors from 1891 to 1928. Brookings Hall and Brookings Quadrangle both are named after Robert Brookings. Millbrook Square Apartments, Millbrook Building, and the Millbrook Pedestrian Overpass all also adorn the Millbrook name.