Auguste Ricard de Montferrand (1786-1858). Plan of existing building under construction. 1818-1820. Ink and wash on fine waxed laid paper (55.5 x 57 cm); pasted on a thick paper mount (60.5 x 63.5 cm). Lower left: signature "Auguste de Monferrand" and stamp "L'architecte de SMI Travaux de l'Eglise d'Isaac"; long annotation lower right: "The new foundations are finished 30 feet deep from the ground, built on stilts whose vuide is equal to the full. All main points and corners are built of granite of great proportion. There is no invert above the piles, which has been replaced by two granite courses running the entire length of the building. The entire structure forms a solid mass, with beautiful underground passageways running all the way around the building. A total of 48 stoves have been installed to heat the building by means of a larger number of heating vents cut into the interior base of the church. Total demolition will be completed in July. The underground passages have been lined with ashlar, they are decorated with a niche, and the staircases leading up to them are made of granite." Огюст Рикар де Монферран (1786-1858). План имеющегося соружения в процессе строительства. 1818-1820. Тонкая бумага верже (восковка) (55,5 х 57 см), наклееннная на плотный лист бумаги (60,5 х 63,5 см), тушь. Слева внизу: подпись "Auguste de Monferrand" и печать "The architect of SMI Works of the Church of Isaac"; пояснения справа внизу : {Красная часть - новая в здании, черная- сохраненная, желтая-снесенная.... Полный снос будет завершен в течение июля. Подвалы выложены камнем, они украшены нишами. Лестницы, ведущие в подвал, выполнены в граните}.