Thousands of people gathered outside Cardiff's Calennig festivities on Friday night to welcome the new year.
City Hall was the focus of Cardiff's Calennig celebrations
And they can continue their party as the city's year-long centenary celebrations begin.
Cardiff's 100th birthday as a city falls on 28 October 2005 and its 50th birthday as a capital on 20 December.
Cardiff council leader Rodney Berman said: "I want everyone in Wales, not just Cardiff, to join the celebration of the capital's half-century."
Over 50,000 people thronged the streets around the civic centre to watch bands, take a turn on the fairground rides or take to the ice in the council's Winter Wonderland rink.
The evening started early with the Calennig fire trail through Cardiff Castle from 1800 GMT, followed by a sound and light show in Bute Park.
It celebrated the voyage of Captain Scott to the Antarctic, which set out from Cardiff.
Revellers listening to an Abba tribute band watched the new year come in with a firework display over the city, set off as the clock struck midnight for 2005.
King Edward VII granted Cardiff city status in October 1905 and, following a ten-year campaign, it became the nation's capital in December 1955.
Both of these key dates will be marked during the centenary, but celebrations will last all year and are expected to attract thousands of visitors to the city.
Cardiff City Council has also organised special events for St David's Day.
Dr Berman said: "We are in the middle of a rebirth of a fantastic city with all the opportunities and challenges that brings.
"I have every confidence that this significant double anniversary will be a landmark in the history and development of local communities.
"I am sure also that it will be a memorable year we can all celebrate together.
"I invite the citizens of Cardiff, businesses, schools and other organisations and institutions to join in our fun and share our resolve and commitment to making the next century equally as significant and inspiring as the last 100 years for Cardiff and for Wales."