Fiesco liked to invest in art. Among others he possessed a tapestry, depicting the lapidation of Achan and the burning of his family (from the Bible story of Joshua). The fragment reproduced below, is extracted from an Antwerp certification book of 1577 and tells about the unfortunate fate of Fiesco's tapestry. It was stored in the shop of François Spierinck on the premises of the Antwerp carpent weavers (maybe for restoration), but was stolen during the "Spanish Fury" of 4 November 1576 and transported to a place near Paris.

[Transcription] "Jehan Jacomo Fieco, marchant Genevois, résident en ceste ville d'Anvers, constituit Franchois Spierincq, marchant tapiseur, bourgeois de ceste dicte ville, et Florent Dargonde, marchant demourant à Paris, en donnant à eulx et chascun d'eulx, seul et pour le tout, plain povoir, authorité et madement espécial de, pour et au nom de luy, constituant, poursuyr, pourchasser, demander, recouvrer et appréhender une pièche de tapisserie, portant la figure de Achan qui est lapidé et de sa famille qui est bruslée, hors de l'histoire de Josué, contenant en longeur dix aulnes et en haulteur six aulnes, laquelle pièche au sac et pillage de ceste ville, advenu le 4 Novembre dernier passé, a esté prins et ravy au Pand des tapisseurs de ceste dicte ville hors la boutique de Franchois Spierincq, et qui présentement, entre aultres, est arresté au-dehors et près de Paris ... Anno 1577, IIa septembris." [Translation] "Giovanni Giacomo Fiesco, Genoese merchant residing in this city of Antwerp, appoints: François Spierinck, merchant and carpent weaver, citizen of the said city, and Florent Dargonde, merchant residing in Paris, handing over to each and both of them, solely and for the whole, full power, authority and command, to search, pursue, ask, claim and seize for him and in his name a tapestry representing the lapidation of Achan and the burning of his family, from the history of Joshua, length: ten el; heigth: six el, a tapestry which was taken away and stolen during the looting of the city on 4 November last year from the shop of François Spierinck on the premises of the tapestry weavers, which was recently, together with others, seized outside and near Paris ... 2 September 1577."

Antwerp, City Archive, CB 39, fol. 541v

The document below, from the Antwerp register of the aldermen of 3 February 1567, reveals that Fiesco was interested in a small organ belonging to one of his debtors. Fiesco regularly acted as creditor of local shopkeepers in Antwerp. In 1567 he was offered a small organ by the shoemaker Jacob De Hont as a pledge for unpaid debts. Fiesco had the instrument valued by Hans Breebosch (the renowned instrument builder who would later build an organ for the royal chapel of Alcazar (Spanje):

[Transcriptie] "Hans Breebosch ... juravit et affirmavit dat hy ten versuecke vanden voors[creven] Mess[er] Jehan Jacomo Fiesco ... wel en[de] behoorlicken heeft gevisiteert zeker positieff gemerct metten marcke in de margie van dess[er] gestelt dwelck de voors[creven] Mess[er] Jehan Jacomo Fiesco als pande metter minnen in handen gelevert is by Jacob de Hont om daer te verhalen zyn[er] tachtercheyt; dat hy [Breebosch] tselve positieff na synder conscientien schat ende priseert op acht ponden grooten vl[eem]s eens." [Translation] "Hans Breebosch ... swears and affirms that he on the request of the said Sir Jehan Jacomo Fiesca has ... visited a certain small organ marked with a sign in the marge of the same, which the said Sir Jehan Jacomo Fiesco has received as a pledge from Jacob De Hont who thus wanted to repay his debts ... and that he [Breebosch] has conscientiously estimated and priced the same organ at eight pounds grooten vleems."

Antwerp, City Archive, SR313, fol. 237v