I did once wonder if it was originally 'are you going to Scarborough, fair' as there is no fair in Scarborough these days. However, I found out that there was a big, well known annual market in Scarborough.... "Scarborough was granted a market charter in 1253 by King Henry III. The markets started on the 15th August and the event ran for 45 days. This meant merchants from all over Europe (and even further afield) travelled to trade in the town. This is probably the fair that the song is about, as the event was so large entertainers attended, giving the perfect opportunity for songs to be written."