New York City's Oldest School: What Every Parent Should Know About Trinity New York City Private School Series: All about Trinity covers one of the most storied and selective private schools in the country — a K-12 institution that has been shaping young minds since 1709. Here's a quick snapshot of what makes Trinity School stand out: Factor Details Founded 1709 — oldest continually operating school in NYC Location 139 West 91st Street, Upper West Side, Manhattan Grades K-12
