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...