600 BC... that was almost 400 years before the Romans conquered Greece.
The Persians considered a canal/lock system to facilitate naval movement across the isthmus. They didn’t last long enough in Greece to get it done.
:^) Transit of the modern canal is described in one of Clive Cussler’s novels.
https://www.historyofrailroad.com/news/father-railway-diolkos
Stay tuned for the Romans Invented Airplanes . . . Almost series.
They built it there because isthmus be the place to do it.............
https://search.brave.com/search?q=corinth+isthmus+canal
Corinth isthmus canal
The Corinth Isthmus Canal is a 6.3 km (4 miles) long, 24.6 meters (80.7 feet) wide artificial waterway that connects the Gulf of Corinth in the Ionian Sea with the Saronic Gulf in the Aegean Sea. It cuts through the narrow Isthmus of Corinth, separating the Peloponnese peninsula from the Greek mainland.
History
The idea of building a canal across the Isthmus of Corinth dates back to the 7th century BC, when Periander, the ruler of Corinth, proposed the project. However, it was abandoned and replaced with a simpler and less costly overland portage road, known as the Diolkos or stone carriageway. The project was revived in the 19th century, and construction began in 1881. The canal was finally completed in 1893.
Features
Length: 6.3 km (4 miles)
Width: 24.6 meters (80.7 feet) at sea level
Depth: 8.5 meters (27.9 feet)
Locks: None (the canal is dug at sea level)
Maximum ship size: 58 feet wide