"I only went out for a walk, and finally concluded to stay out till sundown, for going out, I found, was really going in." (John Muir, 1938) Building interior and urban interior is understood as a single concept of interior: "the outside is always an inside" (Le Corbusier, 1929). Both are thus related to each other, and under the same system of meaning. Architecture comes from the making of an interior. A city comes out of the making of another interior felt as an undeniable inner demand; a street is "a community room by agreement" (Kahn, 1971) and a square is an open aesthetic room by agreement of community. Urban interior that contains our public life-world is an extension of the concept of interior that building interior contains our private/semipublic life-world. This paper explores the idea of interior and urban interior through literature research. The first site the paper traces is the physical interior, space, and place to figure out their meanings. The second site this paper illustrates is the transposition of the physical interior and the psychic interior, which influences the physical space where we create our own life-world. The last site the paper clarifies is the development of the idea of urban interior and the contextual rationale of urban interior. This ramble from building interior to urban interior discloses a twofold singular interior of both the building and urban interior that explains the meanings of interior, the scopes of interior, and the objects of interior to design and create interior.