The link below will connect you to two views of the Thermopylae battlefield.
I have taken current Google Earth views in three dimensions (east and west) and modified them. Labels identify the location of Leonidas statute, Kolonos Hill (where the last Spartans were killed by arrows), the Middle Hot Gate, and Mt Anopaea, which is where the Persians did their end around to trap the Spartans.
The position of the Marian Gulf has been modified to show its ancient shoreline near the current highway. Twenty centuries of silt have pushed to shoreline some four kilometers northward.