Marie Curie visited Poland often, sometimes alone and sometimes with her family. During one of her visits, she set up the Polish Radium Institute for the research of radiation, a sister institute to the one that she had set up in France. 

During the opening ceremony in 1932, she commemorated the event by planting a small sycamore tree next to the institute. At the time, people did not think much of it, but over the years the tree grew to be a respectable 62 feet (19 meters) high.

Sometime before that, the was officially adopted by the institute. A small sign was attached to it that says., “Souvenir tree, planted on the day of the opening of the Radium Institute on May 29, 1932, by Marie Sklodowska-Curie.” The tree is lovingly called “Maria.”