Archaeological collections will be displayed at St Fagans National History Museum as part of plans to redevelop museums in Wales.
Objects will be moved from the National Museum Cardiff in the city's Cathays Park to nearby St Fagans to show the "wider context" of Wales' history.
National Museum Wales also said the full range of its art collection would be shown in a series of galleries at National Museum Cardiff by 2009.
Science displays will also be improved.
Details of the changes will be unveiled by the heritage minister Alun Ffred Jones at the National Eisteddfod in Cardiff later.
They come after a series of consultations with museum visitors.
National Museum Wales said it hopes to further enhance the nation's history, art and science collections as part of a long-term redevelopment plan.
It said by improving its scientific collections, the museum would have a better platform from which to contribute to contemporary debates about climate change, helping people understand today's environmental crisis.
It would also enable researchers to monitor the changes to the natural world.
Michael Houlihan, director general of National Museum Wales, said: "I love museums and galleries - they make us consider why the present is at it is, and what the future might hold.
"We want to continue to enthuse our visitors, offering the opportunity to learn through collection items, be inspired and feel connected to the museums as iconic symbols of what Wales is all about."
Last year, the highest annual total of visits were made to Wales' seven national museums, which are all free to visitors.