I was cheated ...
According to the 2003-2004 Official Tourist Guide, this lighthouse "was a strategic communications point during the two World Wars. It was here, in 1904, that Marconi installed North America's first maritime radio station." So, if the Guide is not cheating, Marconi used more than one lighthouse.
In 1901, Marconi received the first trans-Atlantic wireless message at a position near the Cabot Tower, the letter "S" in Morse Code sent from Cornwall, England.
In 1901, Marconi received the first trans-Atlantic wireless message at a position near the Cabot Tower, the letter "S" in Morse Code sent from Cornwall, England.