Which convenience would not have possible for Romans without arches?

Without arches, the Romans would have struggled to create large and stable structures, particularly in their aqueduct systems. Arches allowed for the construction of long spans and elevated channels, enabling the transport of water over great distances and varied terrain. This engineering innovation was crucial for supplying cities with fresh water, supporting public health and urban growth. Consequently, many of Rome's monumental buildings and infrastructure would not have been feasible without the arch.