Practical tip for hot summer days. The çırağan palace kempinski hotel on the bosphorus has this gorgeous lobby with marble bathrooms and powerful air conditioning. Security doesnt bother you if you walk in confidently and use the facilities

Perfect spot to cool down between sightseeing, use proper bathrooms, maybe grab overpriced but decent coffee if you want to sit for a while. The palace gardens are accessible too if you buy a drink at the café. Learned this trick after nearly melting in sultanahmet during august