The book of the famous American theoretical physicist S. Weinberg contains an exposition of the foundations of the special theory of relativity and the theory of gravity, questions of their empirical verification, as well as a brief excursion into the history of the creation of these theories and their connections with the geometry of space-time. The most established astrophysical applications of the theory of gravity are described in detail. A critical analysis of the main cosmological models and a detailed discussion of their compliance with the data of modern astronomical observations are given. The book contains a detailed and well-compiled bibliography, which facilitates the orientation of the reader in modern literature. The book is designed for scientists, graduate students, students and teachers interested in the problems of gravity and cosmology.