The visitors were spotted posing alongside the poster in Scotland’s capital city with one of them holding up a camera to take a snap.
Andy Glidden, 54, was on his way to work when he spotted the group smiling for pictures.
The owner of a marketing company took a double-take as he walked past the bizarre scene and took several photos as he did so.
On an overcast day, Andy saw three tourists pose next to the bright Vodafone branded photograph of the famous castle.
They stood next to the picture for around four minutes and Andy says that at no point did they over their shoulder to see the real thing.
He said: “I spotted a group taking a picture of themselves in front of a photograph of Edinburgh Castle in a Vodafone shop window.
“It struck me as quite amusing since the actual Edinburgh Castle was right there, looming large and beautiful in the background.
“They were taking pictures for around three to four minutes and at no point did they appear to look at the castle.”
Andy took the picture back in May this year but it re-surfaced online this month when Twitter user Laura Lawson posted it to her followers and it was shared thousands of times.
Laura wrote: “Tourists in Edinburgh are a different breed. Turn around and get a pic with the actual castle you melts ߘ? #edinburgh”