Military organisers estimated that 70,000 people attended a 'Meet the Forces' day in Cardiff Bay on Sunday, at the end of the Nato summit Wales week.
Police have hailed the security operation - the largest the UK has ever seen - as a success, with 31 arrests made in total.
World leaders including Barack Obama left Wales on Friday, praising Newport and Cardiff for a warm welcome.
HMS Duncan, one of most advanced warships the Royal Navy has ever built, has arrived in Cardiff today ahead of the NATO summit.
It will be joined this week by ships from five other NATO member states, and host a working dinner for world leaders on Thursday.
The warship was eventually able to berth, hours behind schedule, after it was delayed from entering the port due to a technical problem with one of the lock gates.
It did not stop hundreds of people turning out to welcome HMS Duncan to the city.
Tom Sheldrick reports:
Top policeman at Nato Summit says stun grenades were destroyed an hour before they were set to explode in path of world leaders.
'Meet the Forces' day was a crowd puller on Sunday as warships open up their decks in Cardiff Bay following Nato summit.
The day began with a spectacular fly-past over Cardiff and Newport by Nato aircraft.