The National Portrait Gallery in London will close for three years as part of a £35.5 million redevelopment project.
The gallery's art will travel across the UK as the works to create a new main entrance are taking place.
There are also plans to "bring back to life" the gallery's East wing, which has been closed to the public, and create a public forecourt.
The Gallery in St Martin's Place will close to the public from June 2020 until spring 2023.
'Unique and important'
It will loan hundreds of works from its collection during the period of redevelopment while, "essential building works take place".
The gallery said 300 portraits a year would "travel to regions across the UK from Cornwall to Edinburgh".
New regional shows include an exhibition in partnership with York Art Gallery in 2021, an exhibition of Tudor portraits curated in partnership with the Holburne Museum, Bath, in 2022 and projects with National Museums Liverpool, Laing Art Gallery, Newcastle and the Scottish National Portrait Gallery.
Dr Nicholas Cullinan, director of the National Portrait Gallery, said: "This is a unique and important chapter in our history as we embark on our journey to deliver a transformed National Portrait Gallery, which will enable us to become more welcoming and engaging to all and fulfil our role as the nation's family album. We are delighted to be able to partner with organisations across the UK and internationally to share our Collection to new and existing audiences."