The crossword solution for the term 'OLD PORT ON THE TIBER' is OSTIA, a five-letter word. Ostia was an ancient Roman port city located at the mouth of the Tiber River in Italy. It was founded in the 4th century BC and served as the main port of Rome until the Middle Ages. Ostia was an important trading center and was known for its large harbor and bustling marketplaces. Today, it is a popular tourist destination and a reminder of the city's rich history.