The moved Hydro Systems to craft its own masterpiece of structural engineering and modern design. Borrowing from the fluid arc of the monument, the elegant curves of the Gateway tub reach skyward to provide bathers with a deep cradle of comfort. Just as its inspiration sets a breathtaking panorama, the Gateway celebrates the journey into vast open spaces with a modern yet timeless aesthetic. For over 50 years, the riverfront of downtown St. Louis has lured visitors to experience the splendor of its presence. The curved stainless steel structure stands majestically at 630 feet in height, making it the nation’s tallest man-made monument. Designed by lauded architect Eero Saarinen to commemorate the westward expansion of the United States, the is an iconic symbol of American promise that is celebrated for its technical structuring and contribution to modern architecture at once.