Walkups, also known as walk-up apartment buildings or brownstones, are common in many urban areas. These buildings typically have several floors with multiple small apartments, each accessed via a staircase rather than an elevator. Walkups is a colloquial term, and there are several synonyms that are more formal or specific. For example, "multi-level apartment building" or "low-rise apartment complex" describe the structure without referencing the specific access method. "Staircase apartment building" or "walk-up apartments" are more specific and describe the type of building. Other terms that may be used include "tenement building" or "row house" which refer to specific types of walkups found in certain regions or historical periods.