A Roman bridge is a really old kind of bridge that was built by the Ancient Romans a long, long time ago. It was made of big blocks of stone, and was really sturdy so that people could cross it safely. The Roman bridge had a really cool design that used arches to hold it up.
An arch is a curved shape made out of stones that are put together in a special way. It is kind of like when you build a tower using blocks, but the blocks are all leaning inwards to make a curve. This makes the bridge really strong because the weight of the people and things crossing it is spread out evenly across the arch.
The Roman bridge was really important because it allowed people to cross rivers or valleys without getting wet or having to go a long way around. The bridge was built over a foundation of stone pillars that reached down deep into the ground to make sure it stayed up.
Today you can still see some Roman bridges in different parts of the world, like in Europe and the Middle East. They are amazing to look at and people can still walk across them just like Ancient Romans did over two thousand years ago!