This thesis surveys these 3 key studies of architectural heritage and urban transformations by questioning the moral aspect of Georges-Eugène Haussmann, John Ruskin and Gustavo Giovannoni. While heritage is often treated as a technical or aesthetic issue, this work argues it is primarily an ethical one: decisions about what to preserve, destroy, or reinterpret shape collective memory, social texture, and the future identity of cities. With the help of philosophical ethics and architectural theory, the study articulates a critical framework based on typology, tectonics, and topology, to interrogate the values embedded in urban form. Architectural history perspectives of Paris, Subiaco, and Venice collectively evidence the ethical argument that each of the three men expounds-from Haussmann's utilitarian rationalism to Ruskin's moral idealism, to Giovannoni's calibrated pragmatism.