After prior experiments in 1894-1895 in the attic of Villa Griffone (the 'Silkworm Room'), Guglielmo Marconi connects a grounded antenna to his transmitter and, in the summer of 1895, succeeds in transmitting radiotelegraphic signals over a physical obstacle — Celestini hill — at a distance of about two kilometres. This is the foundational experiment that precedes his transatlantic transmission of 1901 by six years.