"The open-air Yorkshire Sculpture Park has been named the museum of the year.
The judges described it as "a truly outstanding museum with a bold artistic vision".
The park, situated in the grounds of Bretton Hall in Wakefield, was first opened to the public in 1977.
Picking up the £100,000 prize, founder Peter Murray said: "We've tried so hard to develop something which is unique not just in this country but also in Europe and beyond.
"This award makes us feel we are moving in the right direction."
The park has held exhibitions for the likes of Eduardo Paolozzi, Lynne Chadwick and Ai Weiwei. Its collection of works by Henry Moore is one of the largest open-air displays of his bronzes in Europe.
The museum of the year shortlist included the Hayward Gallery and the Tate Britain in London and the Ditchling Museum of Art in East Sussex."