There's a letter in Old English called thorn. It looks like this:

The word THE was written like this:

And then the printing revolution began. Early printers didn't have the thorn in their bag of letters so they substituted the letter Y for the thorn. So we had this kind of thing:

Ye cat sat on ye mat

Except the YE was still pronounced THE. It was still said like this:

The cat sat on the mat

So, if you see an old sign like this:

don't forget to annoy everyone with the fact that it's pronounced THE old Curiosity Shop and not YEE old Curiosity Shop.