An architect was a son of Johann Daniel Felsko who was a chief architect of Riga between 1843 and 1879. From 1860 to 1863, he worked in his father’s architectural office. Between 1863 and 1865, Karl Johann studied at a building school in Siegen (Westphalia, Germany), then he continued his studies at the Berlin Building Academy (1865–1866) and then at the Imperial Academy of Arts in Saint Petersburg (1866–1867) where he earned a degree of a freelance artist. In 1867, he started to work as a building inspector at the Riga City Board and as a drawing teacher in the School of Crafts. Between 1875 and 1887 he worked as an assistant in Riga Polytechnic Institute. At the turn of the 20th century, he worked as an architect for the Riga House-Owner Credit Society and he was an official expert of the City Construction Board on architectural and artistic issues. He was a very prolific architect: several factories, more than 120 multi-storey residential buildings and numerous wooden houses were constructed in Riga to his designs. Almost all buildings designed by K. J. Felsko have sophisticated eclectic façade compositions, mostly executed in a sculpturesque Neo-Renaissance manner. The house at Blaumaņa iela 28 (1903) also includes ornamental reliefs characteristic of Art Nouveau.