The Pylons of Messina are two free-standing steel towers, the Sicilian one in Torre Faro and the Calabrian one in Villa San Giovanni. They were used from 1955 to 1994 to carry a 220 kilovolt (150 kilovolt until 1971) power line across the Strait of Messina, between the Scilla substation in Calabria on the Italian mainland at and the Messina-Santo substation in Sicily at . Design The two pylons, built in 1955, are both free-standing steel towers. Each stands on an cross-shaped base and is equipped with a crossbar that carries four conductors at a height of , and another V-shaped structure at the top which carries two additional conductors in addition to ground wires. In contrast to more conventional pylon design, the corners of the pylons are arranged diagonally along the direction of the course of the line. The pylons of Messina were the model for the Elbe Crossing 1 in Germany and were, until the completion of Elbe Crossing 2, the tallest pylons in the world. They did however have the longest span of any hydroelectric crossing ever built at 3646 meters, even greater than that of the current record holder the Zhoushan Island Overhead Powerline Tie at 2,700 meters. The span was able to be so large because there wasn't a need for a high clearance, the conductors weren't as heavy and because the east tower was built on elevated ground approximately 163 m (536 ft) asl, giving the tower a total elevation of 396 m (1,300 ft) above sea level. After their completion, the oscillation of the structures and their maximum deflections were determined in a very unusual manner: engineers mounted three rockets with a thrust of 9800 kilonewtons on top of the pylons and ignited them. The line had switching stations at each end of the span. At the Calabrian station, Cannitello, (), the conductors were fixed tightly to a strainer portal. At the Sicilian station at Torre Faro (), the conductors were strained by a device providing constant force, which was situated in a building with two inspiring towers, the so-called Morandi Towers (italian Torri Morandi), designed by the Italian builder Riccardo Morandi. Conductors Until 1971, the electrical service consisted of a single 150 kV three-phase AC system. Four conductors, of which one was used as backup, were installed on the crossbar of the pylon. In 1971 the voltage was increased to 220 kV