Complex sentence: The Pontcysyllte Aqueduct was built by Thomas Telford in 1805 and is the largest aqueduct in the United Kingdom; it carries the Llangollen Canal over the River Dee and is a World Heritage Site, being considered a masterpiece of civil engineering.
Split into simpler sentences: The Pontcysyllte Aqueduct was built by Thomas Telford in 1805 and is the largest aqueduct in the United Kingdom. It carries the Llangollen Canal over the River Dee and is a World Heritage Site, being considered a masterpiece of civil engineering.