The roof is curved. It may be of a regular round arched shape, or more irregularly curved when viewed in section.
Curved roof, Rogers Arena, Vancouver, Canada (S. Brzev)
Curved roof (earthen dome), Iran (F. Naeim,)
Irregular curved roof, Canada (S. Brzev)
Regular curved roof, Canada (S. Brzev)
Curved roof shape, Beijing Capital International Airport, China (S. Brzev)