Tyne & Wear Archives & Museums is expanding and changing its name to North East Museums.
The organisation currently manage nine sites, but from April 1, 2025, they will also manage Northumberland County Council's museum venues.
This will include Woodhorn Museum in Ashington, Hexham Old Gaol, and Morpeth Chantry Bagpipe Museum.
It will bring the number of venues managed by the organisation, which also looks after the Archives for Tyne and Wear, to 12.
Gateshead Council, Newcastle City Council, North Tyneside Council, South Tyneside Council, Newcastle University, and from April, Northumberland County Council are included in the partnership.
Keith Merrin, director of North East Museums, said: "This is a hugely positive and significant moment for both our organisation and our partners to ensure that by working together we can deliver the best museums, galleries and archives for the people of our region and visitors from all over the world.
Chris Mullin, Chair of North East Museums Strategic Board, said: "We welcome the opportunity to work with Northumberland County Council bringing more museums into our partnership.
Museums and galleries play an important role in the cultural life of the region and working together we aim to provide a consistent high-quality experience for all our communities and visitors to the region."
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