Traffic can be stressful in Athens especially when hailing taxis during peak hour. Be wary of a small percentage of dishonest taxi drivers. And keep in mind that smaller museums and some tourist sights close early.
Health conditions in Athens are generally excellent and tap water is drinkable. The heat in summer can be stifling, so drink plenty of water to avoid dehydration and heat exhaustion, and wear sunscreen, sensible light clothing and a hat.
Like anywhere else, practise the usual precautions when it comes to safe sex; condoms are available at pharmacies and supermarkets.
Africa
