The Aqua Appia was the first Roman aqueduct. It was constructed in 312 BCE by Appius Claudius Caecus, the same Roman censor who also built the important Via Appia. The Aqua Appia flowed for 16.4 km into the city of Rome through the Porta Maggiore, and emptied into the Forum Boarium, near the Porta Trigemina. Nearly all of its length was underground, which was necessary because of the relative heights of its source and destination, and afforded it protection from attackers during the Samnite Wars that were underway during its construction. It dropped only 10 m over its entire length, making it a remarkable engineering achievement for its day.