The article deals with two unknown projects made by the Swiss-Italian architect Pietro Antonio Trezzini, who was active in Russiabetween 1726 and 1751. According to the Commission of the Senate,in 1747 Trezzini designed a five-domed cathedral in Stavropol, forwhich he provided two design options. One of these projects, whichwas approved by Empress Elizaveta Petrovna, was realized between1750 and 1757. In both projects, Trezzini presented the cathedralas a monumental five-domed centrally planned church, which isan integral part of Trezzini’s designs. All but one of the Orthodoxchurches designed by the architect had five domes (we know of13 such designs, including all the alternative versions). AlthoughTrezzini was not a initiator of this new type of five-domed centrallyplanned church, his work displays the most mature and diversedevelopment of this approach in Russian Baroque architecture. The article describes the general features of Trezziniʼs churches andcertain individual ones as well.Trezzini’s projects for five-domed churches were directly relatedto the revival of a traditional type of Orthodox church proclaimedby the Empress Elizaveta Petrovna. This idea was widely reflected inRussian church architecture of the time, but its concrete realisationwas rather varied. An attempt is made in article to characterise thissituation by briefly focusing on a comparison of Trezzini’s designsand the five-domed centrally planned churches designed by otherarchitects.The five-domed churches, which were revived in mid-18th centuryRussia and persistently promoted as a national and Orthodox solution,actually had nothing in common with local medieval tradition.Typologically, the five-domed Russian churches of the mid-18thcentury were rooted in European architecture, namely in ItalianRenaissance and Central European Baroque architecture. The mostimportant European sources of inspiration were probably St Peter’sCathedral in Rome (a project by Michelangelo), the Church of StCatherine in Stockholm and the Frauenkirche in Dresden, which theleading mid-18th century architects in Russia were undoubtedlyfamiliar with European, primarily Italian, churches with twosymmetrically placed towers on the western facade and a domeover the intersection, for example, Sant’Agnese in Agone in Rome,should also be taken into consideration.