Giustiniano Participazio[1] (Latin: Agnellus Iustinianus Particiacus; died 829) was the eleventh (traditional) or ninth (historical) Doge of Venice from 825 to his death.
[3] The Byzantine Emperor, Michael II, offered military support to Venice in return for a contingent of Venetians in his expedition against the Aghlabid expeditionary force at Sicily.
While the contest (fomented by Charlemagne and by Lothair I) between the patriarchs of Grado and Aquileia over the Istrian bishoprics continued, Giustiniano worked to increase the prestige of the Venetian church itself.
Giustiniano decided to build a ducal chapel dedicated to Saint Mark to house his remains: the first Basilica di San Marco in Venice.
[4] Giustiniano recalled his brother Giovanni from Constantinople, because he had no sons by his wife, and appointed him to continue the construction of the new church for Venice's new patron saint.