The Tate Britain art gallery in London has raised the £45m required to complete a major renovation.
Nine of the building's gallery rooms are being refurbished, as are the entrance area and other public spaces.
The target has been reached thanks to a £4.9m grant from the Heritage Lottery Fund and £1m given by Tate Members.
The rest has been donated by private benefactors. The Tate fears if tax relief on donations is capped, such fundraising would prove difficult.
"Philanthropy has made a crucial difference to our ability to renovate these galleries and produce these new displays," Tate director Sir Nicholas Serota told BBC News.
"We all fear that the proposed cap on donations will discourage individuals from making this kind of donation."
The Tate's British art collection will be re-hung in a new chronological display in the refurbished galleries.
They will have "much improved illumination", mainly thanks to increased natural lighting, while the reception will be moved from the rotunda to its original position in the foyer.
Donors to the project include oil trader Ian Taylor and the Sainsbury family and philanthropist Dame Vivien Duffield, daughter of tycoon Charles Clore.
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