6Copenhagen, Denmark

Copenhagenโ€™s charming old port area, Nyhavn, connects the oldest part of Copenhagen to the sea and was once a bustling hive of activity โ€” all of it legal.Since it was many sailorsโ€™ 1st port of call into town, the area was a red-light district with many taverns & brothels available for men who had been at sea too long.