Charles began his trip in Belfast yesterday will today be joined in Northern Ireland by Camilla.
The British royal couple will then travel south tomorrow for an official visit.
The visit to Ireland is at the request of the Government and follows Charles and Camilla’s trip to the country this time last year when the Prince toured the place where his great-uncle, Lord Mountbatten, was murdered by the IRA in 1979.
A Clarence House spokesman said: “The visits will recognise the warm friendship that exists between both countries, promoting understanding of their respective heritage and celebrating the best that each has to offer.”
Charles began his visit to Belfast touring the Centre for Secure Information Technologies (CSIT) at the Institute of Electronics, Communications and Information Technology (ECIT) at Queen’s University. He was briefed on the work of the institute and CSIT and toured a laboratory to watch a demonstration on the weather satellite technology the centre is researching and will learn more about cyber-security software.
During their trip to Northern Ireland the couple will visit a number of successful local businesses, some of which work in the food and drink sector, as 2016 is the Northern Ireland Year of Food and Drink.
Earlier this month, Charles attended an event at Fortnum and Mason in London promoting food and produce from Northern Ireland .
The heir to the British throne and his wife will also host a musical evening at Hillsborough Castle which will feature an eclectic programme, with performances from the DIT Harp Ensemble from the Dublin Conservatory of Music & Drama, the Belfast Opera, the “Folk & Trad” group of the Royal Irish Regiment and an appearance by comedian Tim McGarry.
During his visit to Ireland in May last year Charles made an emotional trip to Mullaghmore in Co Sligo — the picturesque fishing village where his beloved grand uncle Lord Mountbatten and three others were murdered by the IRA in 1979.
At the time he described Mountbatten as the “grandfather I never had’’, and said the murders had given him a deep understanding of the pain suffered by victims of the 30-year Northern Ireland conflict.
Tomorrow, the couple will visit Donegal Town and celebrate the area’s heritage by visiting Magee’s — a local company which has produced tweed for 150 years.
At the Letterkenny Institute of Technology, Charles will meet local entrepreneurs and learn more about the institute’s cross-border programmes, while Camilla will visit a local school.
Finally, at Glenveagh Castle, the couple will tour the gardens and meet children who have been learning about some of the conservation work in Glenveagh National Park.