Councils in Belfast and Derry have launched a joint bid for the European Capital of Culture title in 2023.
They hope to impress judges with the diversity of their offering and experience in hosting similar major events.
Belfast previously failed in an attempt to host the 2008 event, while Derry was UK City of Culture in 2013.
Derry City and Strabane District Council Mayor Maoliosa McHugh said: "In Belfast and Derry we have a similar situation with a number of different cultural groupings and this will link those cultures together.
"This bid is a conduit for that co-operation. It helps to move things on in Belfast and Derry and is an example to the rest of Europe.
"Every country within Europe is made up of many different cultures and they cope well with that."
A special launch event was held in Derry's Guildhall on Wednesday.
Belfast Lord Mayor Nuala McAllister said: "Our shared culture is one of the key selling points, the other cities in the UK will be doing single bids."
Every year, two cities receive the title of Capital of Culture from the European Union.
The accolade entails organising a series of cultural events and can provide a fillip to the economy and boost investment and tourism.
In 2023 it will be hosted by a UK city alongside a representative of Hungary.
The UK was already nominated as a host before the country voted to leave the European Union.
Others in the running for the title include Leeds, Dundee and Milton Keynes.
Derry's spell as UK City of Culture four years ago, a separate event, included highlights such as the Turner Prize for modern art and Lumiere, a dramatic and spectacular light show which attracted thousands of spectators.
Belfast and Derry councils are encouraging ideas from the public as they begin to frame their offering and are encouraging people to communicate via social media using the hashtag #backourbid2023.