"The n-Body Problem in General Relativity" is a technical book that addresses the relativistic aspects of the n-body problem in celestial mechanics. It is part of a monograph series led by Henri Villat, focusing on the theory of relativity. The book is aimed at readers who have a basic understanding of absolute differential calculus and the theory of relativity. It provides a comprehensible introduction to the complex mathematical concepts necessary for understanding relativistic gravity. The content is presented in a way that is accessible to both students and professionals who wish to familiarize themselves with the fundamentals of the theory of relativity and its applications in celestial mechanics. The authorship of T. Levi-Civita, a significant mathematician, adds further authority and depth to the work.