To celebrate their victories The Romans were a very successful military power, and they built monuments to commemorate their victories. These monuments often took the form of triumphal arches or columns, and they were often decorated with reliefs depicting the battles that the Romans had won.
To honor their leaders The Romans built monuments to honor their leaders, both living and dead. These monuments could take the form of statues, tombs, or even entire cities.
To boast of their wealth and power The Romans were a very wealthy and powerful empire, and they built monuments to show off their wealth and power. These monuments were often extravagant and opulent, and they were meant to impress visitors from all over the world.
For practical purposes Some Roman monuments were built for practical purposes, such as aqueducts, bridges, and roads. These monuments were essential for the functioning of the Roman Empire, and they allowed the Romans to travel and transport goods throughout their vast territories.