This chapter presents a detailed architectural and historical analysis of one of the most emblematic Neo-Gothic temples in Mexico: the Expiatory Temple of the Sacred Heart of Jesus in León, Guanajuato. Spanning nearly ninety years of construction, the chapter reconstructs the temple’s evolution through its four major construction phases and the succession of architects involved—from Luis G. Olvera (1921–1941) to José María Méndez Córdoba (1973–2009). It highlights the institutional, technical, and financial challenges that delayed completion, while also emphasizing the persistence of religious vision and community support over time. Particular attention is given to the funerary crypts as both functional and symbolic spaces, revealing the temple’s dual role as a site of worship and a place of collective memory. The chapter demonstrates how each architectural intervention contributed to an evolving Neo-Gothic vocabulary that was reinterpreted across decades without losing coherence. Ultimately, the temple stands as a living palimpsest of religious, cultural, and architectural continuity in modern Mexico, where faith-driven architectural projects negotiated with historical contingencies and local capacities.