The article presents the problems of building and maintaining urban transport infrastructure in Warsaw at the turn of the 20th century. The text concerns Kajetan Mościcki (1855-1933), engineer, who was appointed by the acting Mayor of Warsaw, General Sokrates Starynkiewicz, to the position of senior city engineer and head of the municipal construction department, where he worked from 1889 to 1909. During this period, he paved the streets which were worn or damaged by sewerage works with wooden blocks and covered the sidewalks with concrete slabs. He designed the first slip road in the Kingdom of Poland in the form of a spiral, and he also participated in the construction of the oldest road engineering structures made of reinforced concrete, located in Ujazdowski Park and on Karowa street in Warsaw, the first Warsaw power plant and the second city bridge across the Vistula. In addition to his professional activity, Kajetan Mościcki was an inventor in the fields of mechanics and electrical engineering. At the end of his life, he founded an award that the Polish Academy of Arts and Sciences was to grant to Polish scientists for outstanding achievements.