The Tall Ships began to arrive at Belfast Harbour on Friday
Four horns sounded at midday on Thursday to mark the start of the Maritime Festival in Belfast.
Forty Tall Ships, recently arrived from their Atlantic crossing, will be berthed in the city for four days.
The ships will be open to the public to visit on Thursday and over the weekend before the flotilla sets sail in convoy on Sunday.
Nearly half a million people are expected to descend on the city over the weekend.
Belfast beat off competition from other European cities to win the right to welcome the fleet.
The ships left Halifax, Nova Scotia, last month as part of a loop which began in Vigo in Spain and took in Tenerife, Bermuda, Charleston and Boston in the US.
The last Tall Ships Atlantic Challenge race was nine years ago and the only other occasion the ships visited Belfast was in 1991.
Chair of Belfast's Tall Ships board Dr Gerard O'Hare said it would be a fantastic event.
"What people can look forward to is the biggest show in the country, the biggest event ever to be held in Ireland in maritime terms," he said.
"The boats have steadily been appearing on the horizon around the country for the last week, acting as a beacon calling the people to come to Belfast and enjoy the festival and party."
With the anticipated large number of visitors, crowd control and traffic flow have been important factors in the preparations.
Extra police will be on duty and traffic restrictions will be in place around the docks area.
Are you planning to see the Tall Ships in Belfast? Send your pictures to yourpics@bbc.co.uk, text them to 61124 or you have a large file you can upload here.
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