"Hidden gem" The city itself is beautiful but the real beauty is behind the city as you can see in the picture. This place is located between "Oberesslingen" and a suburb of Stuttgart. Its a little tricky.
Basilica Cistern located in Istanbul. Built in 532 - The largest surviving Byzantine cistern in İstanbul, it was constructed using 336 columns, many of which were salvaged from ruined temples and feature fine carved capitals. Its symmetry and sheer grandeur of conception are quite breathtaking, and its cavernous depths make a great retreat on summer days. I am in love with this city.