Reaching the sky
Strasbourg Roman Catholic Cathedral (France) is an awesome piece of architecture built entirely in the Middle Ages. It was the world's tallest building from 1647 to 1874 (the main tower is 142 metres high), and today it's the sixth-tallest church in the world and the highest extant structure built entirely in the Middle Ages.
You must go and see the lovely structure, the sculpted walls, the size of the interior... it's a place to go.
And of course, it's surrounded with a beautiful French old town all around!