Solve this riddle!

I recognize quite a few Greek letters. Whether or not there's others in there too I can't tell you 'cause it's all Greek to me.

Although not all the characters are Greek...

...I think the answer to the puzzle is "It's all Greek to me."

"It's all Greek to me" is certainly a reasonable and acceptable answer, even if the creator of the puzzle had something else in mind.

It's an ancient Greek joke.

Roughly translated, it says:

Stavros : "Hey, Andreas, look at that greek urn!"

Andreas: " What's a greek urn, Stavros?"

Stavros: "About three hundred drachma a year."

that might be considered overly-drachmatic, though.

It most definitely has an answer to be decoded.
Mary queen of scots..