How did the roman build the underground tunnels without light?

The Romans built underground tunnels, such as aqueducts and mines, using a combination of skilled labor, precise surveying, and effective techniques. They relied on basic tools like picks and shovels, and often used torches, oil lamps, or natural light from entrances to illuminate their work. Additionally, they employed a method known as "sighting," where workers would align their tunnels using vertical shafts or reference points above ground. This allowed them to maintain a consistent gradient and direction even without direct light in the tunnels.