Final answer:
The reference information provided does not specify which Xavier University building is a city landmark but illustrates how a library, such as the Library and Learning Center of Vienna University, with distinctive architectural features can serve as a campus landmark.
Step-by-step explanation:
The iconic landmark building at Xavier University that stands out as a city landmark is not explicitly mentioned in the reference information provided. However, based on the description of the impressive features of the Library and Learning Center of Vienna University, it is recognizable that university libraries can become significant landmarks due to their architectural design, size, and multifunctional space that supports the university's academic life.
The polygonal cube design of the Vienna University library, with its distinctive Corten steel facade and curvilinear interior creating a free-form inner canyon, can hold 25,000 students and 1500 staff and includes various spaces for education and social gatherings. Similar landmark features may apply to a landmark building on Xavier University’s campus, but without specific information, we cannot determine which building at Xavier serves as a city landmark.