Istanbul, the former capital of the Roman and Byzantine Empires, is now home to 17 million people, with at least one million commuters crossing the Bosphorus sea between Europe and Asia every day. In 2004, the Turkish government began work on an ambitious plan to connect the two continents by train, building the world’s deepest immersed tunnel under the Bosphorus.

However, the construction of the Marmaray transportation project, which will carry 75,000 passengers per hour in both directions, has been slowed by the city’s rich archaeological history. Engineers have discovered an immense archaeological site that spans 10 football fields, revealing Constantinople’s historic harbor that was lost from view for over 800 years, with 37 Byzantine shipwrecks dating from the 6th to the 11th century remarkably well-preserved. The artifacts uncovered so far have cost the transit system over $30 million and mounting. Archaeologists must work shoulder to shoulder with engineers to uncover the mysteries of Istanbul’s past before their unique window on history closes forever, with the transfer station already under construction.