The Seven Stems Broadcast and Telecommunications Tower would be the tallest man-made structure in the world and one of the most slender, with an aspect ratio of 1:15. The structure works as a bundle of vertical tubes, or stems, joined and stiffened by intermittent outrigger beams. The cylindrical stems, each 14ft in diameter and 2100ft high, are set in a loosely ordered arrangement within a square measuring 140ft on each side.
The Seven Stems has been studied for both a half-acre site adjacent to the New York Stock Exchange and a massive pier extending into New York Harbor from Bayonne, New Jersey.
All but one of the stems tilt slightly in various directions within the underlying square, so that their relationships to one another change as they rise. At vertical intervals of 70ft, outrigger beams connect the stems in a variety of patterns, without creating a closed figure at any one level.
The stems are built up of 7ft tall cylindrical units with a constant outside diameter of 14ft. Each unit consists of an outer shell of curved hot laminated stainless and mild steel plates and an inner wall of raw steel plates. The space between the outer shell and the inner wall diminishes from 48in at the base to 8in at the top of each stem.