Files containing projects, plans, sketches and draughts by little known or even forgotten 19th century architects have turned up, examining the Riga City Council Master Builder and Chief Architect Johann Daniel Felsko's (1813-1902) creative legacy and searching for his projects at the Latvian State History Archive Vidzeme Province Building Board collection No. 10. Altogether works by 24 architects, engineers and draughtsmen have been found in this collection. The overview of already known and newly discovered architects' activities is disproportionate; some draughts or their copies have survived in fragments, in other cases correspondence on building licences testifies to construction activities. Projects mentioned in this article for the most part relate to the period from 1852 to 1865. They give an insight into construction history of Riga as well as Cesis, Limbazi and Dorpat (now Tartu in Estonia). The material is complemented by particular reconstruction and new construction projects for buildings around Riga and Cesis. The 1850s are commonly regarded as a total stagnation period in the history of Latvian architecture and construction, as Crimean War influenced economic life in Riga as well. It is possible that projects discovered in the collection No. 10 will make one to reconsider this conclusion. Plans, draughts and sketches of dwelling houses from the 1860s allow tracing gradual replacement of wooden buildings with stone edifices. But projects from the 1870s-1890s are rarely found there. These projects are especially important because buildings constructed according to them have not always survived till our days, many perished during the 20th century wars. Their visual reconstruction can significantly add to or even alter the overall scene of the 19th century architecture.