I came across two drawings by Heinrich Sielken (1874 - 1942)…
Heinrich Sielken was an architect who was born in Hanover and worked in Bremen from 1920. In 1927 he published an article in the Deutsche Bauzeitung (61. Jahrgang. 1927, Nr. 58, S. 481-485) about the Holy Trinity Church of St Sergius near Moscow. The drawings and the article were most likely created on the same journey.
The first drawing is a view across the Moskva River to the Kremlin. It shows the Taynitskaya tower (Тайницкая башня), the Cathedral of the Archangel and the Ivan the Great Bell Tower.
The second sheet shows the Church of the Ascension of Christ in Kolomenskoye
Sielken later worked for Paul Kossel & Cie. KG, Beton- und Eisenbetonbau-Unternehmung, which carried out the concrete work for the Wulsdorf residential water tower (Wikipedia).