We present to a wide audience a work that belongs to the cycle "Classics of Natural History." The publication was written on the 100th anniversary of the death of Lobachevsky. The main task of this publication is to tell all interested readers about the works of an outstanding domestic mathematician in the original. The book presents several works of the pen Lobachevsky. These are "Geometry," "Geometric studies on the theory of parallel lines" and "Pangeometry." Each monograph represents a round of the author's creative life.