Cabot Tower is a tower in St. John's, Newfoundland and Labrador, situated on Signal Hill. Construction of the tower began in 1898 to commemorate the 400th anniversary of John Cabot's discovery of Newfoundland, and Queen Victoria's Diamond Jubilee.
In 1901, Guglielmo Marconi received the first trans-Atlantic wireless message at a position near the tower, the letter "S" in Morse Code sent from Poldhu, Cornwall, United Kingdom. Cabot Tower is now the centre of the Signal Hill National Historic Site of Canada, with walking trails and an interpretation centre.