This is how Trump describes George Papadopoulos:
Here is a photo of Papadopoulos with the President of Greece.
Here is a photo of George Papadopoulos with Republican elites.
This is how representatives of Greece described their meeting with George Papadopoulos. Notice, they call him a 'national security adviser', maybe that was a fabrication on Papadopoulos part, but apparently Trump played along with it, because he was useful at the time.
Where did Papadopoulos meet with the Greek Representatives? Trump tower.