On June 23, 1921, the centennial of the birth of Mariano Procópio, Alfredo Ferreira Lage opened the museum to select visitors. In that year, Princess Isabel and the Count of Eu were in Juiz de Fora and were able to pay a visit to the museum, having just returned from a recently repealed exile imposed on the royal family by the new republican government in 1889. It was during this time that Alfredo announced his intention to donate his collection to the municipality.