Totally by chance, our scheduled time in Athens falls over the last weekend in Sept which is, apparently, the free entry weekend at the Historic sites. Should we expect massive crowds everywhere? Would it be better to hit the Acropolis on Friday (the day we arrive) when it is not free entry? I am travelling with a 17 year old with mild Autism and, if it is going to be insanely crowed, it may ruin his experience. So, if going the day before the free weekend is advisable, I would much rather do that. Also, I saw on the forum that going to the Acropolis after 5 may give a less crowded experience. Any advice and suggests would be very welcome.