Final answer:
A roof that slopes upward from all sides and joins at the ridge is known as a hipped roof. This design can indicate the importance of a building historically and is present in various architectural styles.
Step-by-step explanation:
A roof that slopes upward from all four sides and is joined at the ridge is called a hipped roof. This architectural feature is commonly found in various building designs, such as the imperial structures of ancient times where buildings with a double-eave hipped roof showcased the command of the emperor. In contrast, buildings of lesser importance might have a single eave or a gable roof. The shape and complexity of a roof can signify the status or function of a building, as seen in the temple front house style of the New England Large houses or the iconic Casa Batllo with its dragon-back-like roof arched upwards adorned with colorful ceramic tiles.