St David's Day celebrations in Wales and beyond
Prince Charles visited Carmarthenshire to mark St David's Day, as events take place at home and across the world.
Parades were staged in Cardiff and Wrexham as part of celebrations.
And St David's Day is also being marked in places as far afield as China and New York.
Meanwhile, the Archbishop of Wales has given a sermon, urging people in Wales to keep "our identity" without being "narrowly nationalistic".
The Welsh dragon is flying above Downing Street, while Welsh Secretary Cheryl Gillan is due to read at the annual St David's Day chapel service at the House of Commons.
Prince Charles visited Llandovery College, to attend an eisteddfod.
He met former Llandovery head boy and 2007 X Factor contestant Rhydian Roberts, who sang at the event.
The prince praised the performances he had seen, adding: "But I feel embarrassed because I think unless you sing or you dance you feel pointless standing up here.
"I knew I should have taken those lessons from Cheryl Cole, tango dancing," he joked.
The prince also met local businesses affiliated to the Cambrian Mountains Initiative which promotes rural enterprise.
There will be St David's Day events in cities across the United States, as part of Wales Week.
St David's Day is also being celebrated in Monaco where Dame Shirley Bassey is guest of honour at a lunch hosted by the Monaco Wales Association and attended by Prince Albert of Monaco.
The association was founded by Mark Thomas, son of former Welsh rugby captain Clem Thomas.
Later this week in New York, Welsh actress Catherine Zeta-Jones - last week awarded the CBE at Buckingham Palace - will be honoured for promoting Wales around the world.
The award is being presented by the St David's Society of the State of New York at its annual dinner on 4 March.
US Secretary of State Hilary Clinton sent over her best wishes to the "people of Wales".
"On behalf of President Obama and the people of the United States, I congratulate the people of Wales as you celebrate St David's Day," she said.
"The United States is enriched by years of influence from Welsh-Americans."
Archbishop of Wales Dr Barry Morgan appealed for a celebration of national identity, without being "aggressive to outsiders" in a sermon at the chapel of the University of Wales Trinity Saint David, Lampeter.
"The challenge we face, as a nation, is keeping our identity and rejoicing in it without at the same time becoming narrowly nationalistic, xenophobic even, exclusive," he said.
"Nor is this a problem just for Wales. You only have to read the correspondence columns of the daily papers to see the extreme views that people have about asylum seekers.
"That debate is about race and nationality but of course we all like boundaries and perhaps we all need boundaries because boundaries give us a sense of security. They help to define who we are - family and non-family, Welsh and non-Welsh."
Welsh monument society Cadw is offering free admission to all its castles and other historic buildings.
First Minister Carwyn Jones, in his St David's Day message, said Wales would continue to build on its history and heritage to attract visitors.
"These have been difficult times for the economy and Wales has taken its share of knocks but I have no doubt that this is a country with a great future," he said.
Welsh Secretary Cheryl Gillan was welcoming a group of children as part of an annual outing by cancer charity Latch, as well as being presented with daffodils for the Wales Office.
"As a child we always dressed up in traditional costume and for many children, today is an opportunity to do just that," said Mrs Gillan.
In Cardiff, Wales coach Gary Speed will take part in a public parade leaving City Hall at 1230 GMT, before finishing in front of St David's Hall at 1300GMT where there will be music and entertainment.
About 600 school children will march around Colwyn Bay from 1000 GMT before meeting at St Paul's Church for a concert.
And in Wrexham a parade starts at Eagles Meadow at 1330 GMT before arriving at Llywn Isaf, near the Guildhall, for the national anthem before 1400 GMT.
Outside Wales a number of events are being planned.
In London, people will be invited to sample award-winning Welsh food and drink at stalls at Marble Arch and Oxford Street.
In China, Wales Week in Chongqing runs until 6 March highlighting exchanges covering industry and education.
And in the United States, an exhibition by Llanidloes-born photographer Cambridge Jones opens at the Los Angeles Public Art Gallery on Wednesday, featuring photos of Welsh celebrities such as Katherine Jenkins, Bryn Terfel, Ioan Gruffudd and Michael Sheen.