Marshal Józef Piłsudski died on May 12, 1935. Shortly after his death, on December 1, 1936, a competition for the Marshal's sarcophagus was announced. The deadline for submitting projects was set for March 15, 1937. Then it was extended until April 30, 1937. The Competition Jury was held on May 19 and 20. The winner was not determined, and the awarded projects were further analyzed in accordance with the guidelines of the Competition Jury. At the meeting on July 19 and 20, 1937, three works were selected: by Jan Szczepkowski, Mikołaj Kułak and Bazyli Wojtowicz together with Stanisław Repeta. The authors were commissioned to make models in a 1: 1 scale. On June 22, 1938, the Competition Jury recognized Jan Szczepkowski's design as the best and the artist asked to complete it. In his design of the sarcophagus, Szczepkowski referred to the sarcophagus of Kazimierz Jagiellończyk. The sculptor clearly showed the characteristic features of the physiognomy of Marshal Józef Piłsudski. Strong eyebrows, deep-set eyes, prominent mustache with a barely visible lower lip. The face was modeled in a way that emphasizes the dignity of the deceased and the majesty of death itself. At the feet of the deceased, dressed in a long, military coat, he placed an eagle - a bird with symbolism important for the history of Poland. The special role of the deceased was additionally indicated by the mace held in the right hand and a wreath of oak leaves around the head. Szczepkowski carried out the design of the sarcophagus cover in his characteristic style, decorative, simplified, geometrized and referring to folk art. Especially the Podhale woodcarving.

On May 24, 1939, the Executive Department entrusted Jan Szczepkowski with the execution of a granite version of the cover. After the project had been approved for implementation, its deadline was delayed. The sarcophagus was to be built by Bolesław Sypniewski's stone masonry in Powązki. Even a block of gray-blue granite (or red, according to other sources) was provided. The members of the Committee, together with Jan Szczepkowski, personally went to a quarry in today's Ukraine to supervise the preparation of the stone. Apparently, the order was completed, but in September 1939 the finished sarcophagus was destroyed during the German bombing. Unfortunately, no specific evidence remained. The fate of the plaster project in the first post-war years is not fully known. His condition has certainly deteriorated significantly with passing time. For 45 years of communist rule, there were no conditions in Poland to take any measures to protect the sarcophagus from further destruction. Although, according to Natalia Więcek, who wrote about the project in her work, it is likely that during the organization of the temporary Museum of Jan Szczepkowski in Milanówek, in 1978, the object underwent renovation works. It is also possible that the author himself began some corrective action.

In 2007, the City of Milanówek bought the Waleria villa from the heirs of Jan Szczepkowski together with the entire artistic legacy of the author, which was there for the purpose of establishing the Jan Szczepkowski’s museum. The aforementioned Natalia Więcek in 2015-2016 carried out the conservation of the monument under the supervision of Dr. Janusz Smazy, specialist in stone conservation, assistant professor at the Studio of Conservation and Restoration of Stone Sculpture and Elements of Architecture at the Academy of Fine Arts in Warsaw (Faculty of Conservation and Restoration of Works of Art).