giorno. Both Rossetto and Malvezzi were associated with the Medici court. Preceding these works was a 40-voice motet produced in Munich in 1564 by Orlande de Lassus, which has been lost. When Striggio completed the enormous mass setting, he carried it with him during a diplomatic trip across Europe to strengthen the dynastic relation brought on by the recent marriage of Francesco de' Medici to Johanna of Austria, who was a Habsburg. His trip consisted of a series of visits to new Medici in-laws, including Maximilian II, the Holy Roman Emperor. It was necessary to give them something splendid, and this was likely a performance of the colossal 40 and 60 voice mass, along with a copy for their archives. Leaving Florence in December 1566, he visited Mantua, and then made the difficult winter trek over the Brenner Pass, visiting Vienna, Brno, Munich, and Paris. In June 1567 he made his way to London with the specific purpose of meeting "the virtuosos in the profession of music that were there" (as he wrote in a letter to Francesco I de' Medici, dated 18 May 1567). While in England, he almost certainly met Thomas Tallis, and it is now considered likely that the Missa sopra Ecco sì beato giorno was performed in a private residence – likely the London seat of the Earl of Arundel, Arundel House – in order not to offend the authorities (since performance of the Roman Catholic Mass was at that time prohibited in Protestant England). Loss and recovery After Striggio's exhausting 1567 European tour with his work, it disappeared for more than four centuries. While he left copies of it at several locations he visited – the court of Maximilian II, Holy Roman Emperor, the court of Albrecht V in Munich, the court of Charles IX of France – all copies had been lost. However, a copy of the mass was made in the early 17th century in France, presumably from the copy Striggio left in Paris for Charles IX. Because of several corruptions and copyist errors both on the manuscript and in the card catalogue, when the enormous document, which had been transferred to Louis XV in 1726, from the library of composer Sébastien de Brossard, and then passed to the Paris Bibliothèque nationale, the mass was attributed to an "Alessandro Strusco" and the "40 voices" had been amended to "4 voices" (presumably the copyist