In 1493, the Serenissima asked Gian Paolo Ranieri di Reggio Emilia for a new clock in order to replace the one, called S. Alipio's, situated since 1384 on the fašade of the Basilica of S. Marco. On November 3rd 1495, when the clock was almost ready, the Senate, in accordance with the Procuratori di S. Marco, decided to place it at the entrance of the Mercerie and that a new suitable building should be erected for that occasion.
The construction was completed in two years and decorated by a huge bell and two bronze giants. In 1500 the Senate and the Procuratori di S. Marco decided to erect new edifices on both sides of the tower; this building site was concluded in 1506. In 1755 eight columns were added, in the seventeenth century manner, to reinforce the pillars at the ground level and support the two lateral bodies. By comparative analysis, since the appropriate documents are missing, the author of the enterprise seems to have been Mario Codussi.
This can be deduced from similarities between the great arch and the Capella Bernab˛ in S. Giovanni Crisotomo; between the last order of the tower and the upper part of the Scuola S. Marco; between the profile of the first trabeation of the arch and the third entablature of the front of S. Zaccaria. The Clock Tower, enriched by the splendour of its materials, is one of the most important links between the Piazza and the rest of the city as well as a religious and civil symbol. (reference)
Other landmarks: Christ the Redeemer, Colossus, Delhi pillar, Eiffel tower, Golden Gate bridge, Great Buddha, Guggenheim Museum (Bilbao), Guggenheim Museum (NYC), Normandy bridge, Oresund crossing, Quebec Bridge, Statue of Liberty, Thames Barrier, Titanic, Tower of the Orologio, Washington Monument