 In 1885–1888, Mashkov assisted Konstantin Bykovsky on Devichye Pole campus planning and August Weber on the completion of Polytechnical Museum in Moscow.In 1889–1890 he visited Lipetsk and completed there two schools, a hospital and a prison chapel – at the age of 23.Back in Moscow, Mashkov completed over a dozen buildings still in his twenties, and his masterpiece – the "Sokol" – at the age of 36.