The Answer: Around AD 345
Image idea: the Edicule interior lit by candles.
In late 2017, National Geographic revealed the results. The mortar between the rock and the cross slab dated to around AD 345.
That is exactly the time of Constantine. Before this, the oldest evidence found at the tomb was only around 1,000 years old, from the Crusader era.
The result matched the old written records closely. It suggested that the people who first honoured this tomb in Constantine’s time really did choose this exact spot.