Palace of the Irish Kings.
The fort of Emain Macha in Ireland was once the home of princes and kings of Ulster, and, according to Celtic legend, was built by King Conchobar, who also built two other palaces.
The team go to Navan, the modern-day site of Emain Macha, in search of evidence of the other palaces and attempt to find a connection between what may have been a sacrificial pool and an ancient hill called Haughey's Fort.