The Prince laid the first brick for the St Edmundsbury Cathedral Millennium Tower in 2001 and on Friday he returned to to see it finished.
During a special service in the cathedral, more than 1,000 people heard the Rt Rev Richard Lewis, Bishop for the Diocese of St Edmundsbury and Ipswich, dedicate the new tower.
He said: "His Royal Highness has described this as a spiritual beacon. The events of the past fortnight and yesterday have given those words a special poignancy. The light of faith is badly needed in what can be a dark world."
Before and after the service the royal couple met the public who braved the rain to line the streets and Angel Hill.
Liz Huddlestone, from Bury, said: "Camilla said she was sorry she didn't bring the weather with her. It was a great honour."
Sandra Utting, from Bury, who also spoke to Camilla, said: "She looks lovely, absolutely beautiful. She said I was very lucky to live in Bury as it is such a beautiful place."
The couple viewed examples of Suffolk life and work in a special tented village on Angel Hill and even pulled a pint of beer at the Greene King stand.
Horry Parsons, team leader for tower developer Bluestone, said the couple enjoyed meeting those who had worked on the tower. "Camilla asked where the first brick was and Charles said it was well hidden. One of our guys jokingly asked 'did he see the tower leaning'."
Mr Parsons' grandchildren Zoe and Sophie and great grandchild, Leah presented the royal couple with flowers.
Following the tower visit, The Prince of Wales and his wife travelled to St Nicholas' Hospice, in Bury, to meet patients, staff and volunteers.
The Prince, who is patron of nine hospices around the country, made a speech about the work they do, caring for terminally ill patients.
The Prince said: "I am ceaselessly amazed by the contribution of so many local people like yourselves who give so much devotion to the hospice.
"The people who come here are given a haven of peace and above all the attention of people who listen. Thank God for this wonderful place."
The Royal couple also cut a cake which marked the 21st anniversary of the hospice.
During their tour,they met day-patients, inpatientsand children who are part of the Nicky's Way Scheme which offers help to the recently bereaved.
Day-patient Beatrice Martin, 92, of Thetford, said she spoke to the Prince and found him 'charming'.
The couple then travelled on to Lavenham where they visited the Guildhall and the headquarters of the Suffolk Preservation Society.
The cathedral celebrations stretched into the weekend with a firework spectacular on Saturday night, a gala dinner and music by a brass band, Foden's Richardson Band, and local choirs and groups in the Abbey Gardens.
On Sunday, services were held and at the packed choral evensong there was a standing ovation for the presentation of a gift to James Atwell, Dean of the cathedral, by Bishop Richard.