The Prince of Wales has said he has faith the friendship between Ireland and the UK will endure for generations as he vowed to visit all 32 counties on the island.
Charles made the remarks in a speech, which featured a few words of the Irish language, in front of stars including Sir Kenneth Branagh at the Embassy of Ireland in London.
Along with the Duchess of Cornwall, Charles sat down for an early St Patrick's Day dinner with guests such as the Irish Minister for Foreign Affairs Simon Coveney, comedian Dara O Briain and actors Fiona Shaw and Adrian Dunbar.
The prince's words at the celebration of UK and Irish relations are likely to be interpreted by commentators as partly referring to the importance of the relationship between the two countries amid the challenges presented by Brexit.
Charles, who has toured Ireland every year since 2014, said: "Above all we are friends, we are partners and we are the closest of near neighbours, bound together by everything that we have in common - and by just how far we have come together.
"If I may say so ladies and gentlemen, this is precisely why it has been of such importance to both my wife and myself that we too should visit Ireland so often over these past few years - to experience and celebrate as best we can the unparalleled bonds between our two countries and to highlight just what a fundamental difference they make to us all.
"And I must say I'm slightly amazed to find that we've managed to visit 15 counties already.
"I am quite determined before I drop dead and finally lose my marbles that I should get around to the remaining 17."
Charles added: "And so, as our relationship evolves over the coming months and years, I have both the faith and the hope that the essential friendship between the people of Ireland and the people of the United Kingdom will not only endure but will renew itself for generations to come."
Charles finished his toast by wishing everyone a happy Saint Patrick's Day in Irish: "La Fheile Padraig sona daoibh."
Guests at Wednesday night's dinner feasted on Connemara cured ham and organic Irish salmon.
Camilla wore a green Kaftan, which was a gift from the King of Morocco when the couple visited in 2011.
In a speech, Mr Coveney said it was a privilege to be at the event to celebrate the British-Irish relationship approaching Saint Patrick's Day "at a pretty serious time for everybody".
He added: "All of us here this evening understand that it's not a time of entirely plain sailing in this relationship. There are some big issues at stake."
Mr Coveney said it was important to celebrate the "extraordinarily vibrant and overwhelmingly positive connections" enjoyed by the UK and Ireland.
Before the dinner, Charles and Camilla were shown a new portrait of poet Seamus Heaney by artist Mark Baker.
The Nobel laureate's widow Marie Heaney joined the royal couple in viewing the painting, and told Camilla she thought it was "terrific", adding: "I'm very touched. It's lovely."
Meanwhile, Sir Kenneth said he discussed his upcoming film Artemis Fowl with Charles, and said: "I think he's interested in all things Irish."
Commenting on the importance of celebrating relations between Ireland and the UK, Sir Kenneth said: "Always better to talk than not talk."
Harry Potter star Shaw said she meets the royal couple "regularly", and said events like the one on Wednesday night were important in order to "save the ties between the two countries".
On the issue of Brexit, she said: "What is stupendous is that Europe is protecting that border."
Asked how optimistic he is about the border issue being resolved, Line Of Duty star Dunbar said: "No idea. Nobody knows what's happening. Nobody knows what's going on."
O Briain joked that he would like Brexit chaos to carry on until June when comedy panel show Mock The Week is back, saying: "Frankly I don't want to be doing Mock The Week in a post-Brexit landscape."