Heinrich of Gmunden has had a good deal of credit for this building; so much so that a certain bust, said to be his likeness, was kept in the sacristy of the Certosa; and on the strength of that bust, the Germans erected a statue to him in Gmunden. But as he left Italy in July 1392, dismissed from Milan after a few months there, it is not probable that he could have designed the Certosa in 1396. Count Giulini was the first to draw attention to this error; and a learned archivist, Girolamo L. Calvi, had the good luck to discover in the archives of S. Fedele, the ancient register of the Administration of the building of the Certosa for the year 1396, which settles the matter completely. The master builder was Bernardo da Venezia, and Jacopo da Campione worked with him as designing architect and superintendent. On the official verification of this precious MS. on April 16, 1862, the bust of Heinrich da Gmunden disappeared from the sacristy of the Certosa.
As a proof that the Magistri mentioned were both employed, we will translate a few of the entries of the Provveditore of the Certosa.
"1396. July 26.—In the presence of Pietro Barboti, official of the Administration, Berto Cordono, cordmaker, was paid for 138 lbs. of strong cord, for use in the designing and building of the church and cloister. The cord was consigned in June, at the order of Maestro Bernardo da Venezia, architect of the said laborerium" (Inzignerium dicti laborerii).
"1396. August 14."—(This should, I think, be September 14). After registering several payments of wages to workmen who excavated the foundations, it is written—"Also the above-named Jacopo da Campione, for his superintendence of the works (tantum qui perseveravit superdictis laboreriis), together with the Duke's architects during fourteen days (i.e. the last days of August and the first two of the present September), at the rate of eight imperial soldi a day, as he had to find his own food."
"1396.—The Magistri Jacopo da Campione, Giovannino de Grassi, and Marco da Carona, architects, came from Milan to inspect, order, and build in the aforenamed works" (causa videndi ordinandi et hedificandi). The two latter must have been the Duke's architects spoken of before. All through August and September Jacopo da Campione was backwards and forwards between Milan and Pavia, and Maestro Bernardo also received his salary monthly as chief architect.
Again, on November 22, 1396, we read—"To Master Jacopo da Campione, architect of Milan cathedral (inzignerio ecclesiæ majoris Mediolani), for fourteen days during October and November, in which he remained working and superintending in the said laborerium (Certosa) at his own expense, and in payment for some designs made by him at Milan, and submitted to the Duke's approval here."
On December 4, 1396, the Provveditore notes the purchase of twenty sheets of parchment, most of which were consigned to the Magistri Jacopo da Campione and Cristoforo da Lonigo for the designs of the church. From these entries, it would seem that Jacopo was the architect who drew the designs, and Bernardo da Venezia the master builder who executed them. As a farther proof, there is the deliberation of the Administration of Milan, on March 4, 1397, to which we have already referred, in which it says that Jacopo was in command of the works at Certosa (qui acceptatus est super laboreria Carthusiæ).
Other Campionese names also appear in the registers; such as Domenico Bossi da Campione, who was paid "for four marble slabs, with certain inscriptions, which were placed under the foundations when the Visconti laid the first stone on August 27, 1396;" and "Giovanni da Campione, called Bosio, for three sculptured marble slabs for three reliquaries."
In 1397, Gian Galeazzo, being taken up with affairs of state, ceded the presidency of the Administration of the Certosa Lodge to the Prior of the Carthusians, adding more donations and an endowment. The Prior's first actions were to dismiss Bernardo da Venezia as master builder, and to call Antonio di Marco from Crema. He was son of Marco da Campione, one of the chief architects of Milan cathedral, and brother of Guglielmo di Marco, whom we have also found at Milan in 1387, where he was called as an expert to give judgment on some moot point.
When Antonio entered office, the monastery had twenty-four cells already inhabited by as many monks, under their Abbot, Father Bartolommeo of Ravenna. As soon as the contract was signed, it appears that Antonio returned to Crema, leaving Giovanni Solari da Campione, father of Guiniforte, and Francesco Solari, in charge. In the payments made to Giovanni as chief architect, we find his name written in different ways. In one, "Magister Johanni de Campilioni Ingenerio fabrice Monasterii LXVI." In another, "Magister Johanni di Solerio Inzignero super laboreriis fabrice Monasterii die XIV Maij, pro suo salario LXVI;" sometimes he is merely written as "Johanni Inzegnero."