Lviv gave the world quite few scientists. One of them, Stefan Banach, became one of the most important figures in mathematics of the 20th century. He was a cofounder of the best mathematical journals "Studia Mathematica" . (1892--1945) - Mathematician, born in Krakow, Poland but lived and died in Lviv, He is regarded as one of the founders of functional analysis, and he founded an important school of Polish mathematicians. Made major contributions to the theory of topological vector spaces. In addition, he contributed to measure theory, integration, and orthogonal series. Keywords: Banach space, Hahn-Banach theorem, the Banach-Steinhaus theorem, the Banach-Alaoglu theorem, the Banach fixed point theorem, the Banach-Tarski paradoxical decomposition of a ball and more.