Kato Souli Naval Transmission Facility (Greek: Κέντρο Εκπομπής Κάτω Σουλίου) is a facility used by the Greek Navy for transmitting messages to submarines in the LF-range at Kato Souli near Marathon, Greece. It was commissioned in 1989 and uses as tallest antenna tower a 250-metre-tall guyed mast with umbrella antenna, the tallest structure in Greece. The site has an area of 650 acres. Nearby there was a transmission site of the US Navy with several shortwave transmitters.
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Kato Souli Naval Transmission Facility Wikipedia(Text) CC BY-SA