 He graduated from the Gdańsk University of Technology in 1927 as an architect.Among the most famous and influential Estonian architects, Kotli has created several important landmarks in Tallinn.These include the Estonian Song Festival grounds (1957-1960, with Henno Sepmann & E. Paalmann), the main building of Tallinn University (1938-1940, with Erika Nõva), the Art Fund building (1949-1953) and the administrative building in Kadriorg park (currently the residence of the president of the Republic of Estonia) in conjunction with architect Olev Siinmaa (1937-1938).