What was the greatest of the Incas' many achievements? 3 sentencces for 6th grade

One of the greatest achievements of the Incas was their extensive network of roads and bridges known as the Inca road system, which connected their vast empire. Another significant achievement was their advanced agricultural practices, including terraced farming and irrigation systems, which allowed them to grow crops in the rugged Andean mountains. Additionally, the Incas had a well-organized government and administrative system, including an efficient system of taxation and record-keeping.