Complex sentence: Another attraction is the underground ancient aqueduct also called the'Underground City' which is partially open for tourists.The underground aqueduct was built around 1000 years ago for transportation and water supply across the different parts of the island.
Split into simpler sentences: Another attraction is the ancient underground aqueduct, also called the'Underground City', which is partly open for tourists. It was built about 1,000 years ago for transportation and water supply across the different parts of the island.