The Prince of Wales and Duchess of Cornwall arrive in India today for a nine-day tour to renew and strengthen ties between the UK and the Commonwealth nation.
Charles and Camilla will travel the length and breadth of the Asian country to experience its diverse people and cultures, celebrate the achievements of leading individuals and highlight the work of some of the heir to the throne's own organisations.
Camilla will also be carrying out a number of solo engagements focusing on her interests of literacy, osteoporosis and equestrianism.
The prince turns 65 during his autumn tour and will celebrate the milestone the day before he hosts the Commonwealth Heads of Government Meeting (Chogm) on behalf of the Queen in Sri Lanka.
The heir to the throne will be convening his first Chogm which faces a number of challenging issues, from those concerned about Sri Lanka's alleged human rights abuses to the recent withdrawal of the Gambia from the 'family of nations' after it denounced the body as a "neo-colonial institution".
In a speech made at the University of the West Indies in Trinidad in 2000, titled The Commonwealth In The New Millennium, the prince described the uniqueness and relevance of the organisation.
He said: "I have long had an instinctive sense of the value of the Commonwealth. It encourages and celebrates cultural diversity and makes no attempt to homogenise.''
The prince added: "For me, the Commonwealth is something rather special and worth cherishing. It is as old as I am, and so has been present throughout my life, as something to which the Queen and other members of my family attach great value."
Charles and Camilla have made three official visits to India, the last was in 2010 when the Prince opened the Commonwealth Games in New Delhi.
But this will be their most extensive, with the couple travelling to Dehradun, New Delhi, Mumbai, Pune and Kochi, where they will meet India's top political and business leaders.
Highlights of the trip include the Prince making an off-road trip into an "elephant corridor" in Kerala, and the royal couple attending a gala dinner in Mumbai with a Bollywood flavour.
The royal couple will tour India until November 14 - Charles' birthday - then travel to the Sri Lankan capital Colombo for the Commonwealth summit, staying in the country until November 16.
Their tour begins later today when they fly by chartered plane to the northern city of Dehradun before travelling to the River Ganges, sacred to many Indians, where they will observe the famous sunset Aarti ceremony.
Charles and Camilla will carry out a full day of engagements tomorrow when they visit a military academy and later the prince will tour the Forest Research Institute while Camilla visits the prestigious Doon School, a boarding institution for boys.