2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/86960This is a semipopular introduction to the Special and General Theory of Relativity, with special emphasis on the geometrical aspects of both theories and their physical implications.In Spanish, 20 pages. LaTeX, 8 figures. To appear in the Einstein Special Issue of "Revista Espanola de Fisica"Popular Physicstext