Seriously, what more could you want? The town of Nordlingen in southern Germany is one of Europe’s best kept secrets. Not only did it celebrate its 1100th birthday in 1998, it is also situated slap bang in the middle of the Ries meteorite crater. This was formed 14 million years ago, when an impactor 1.5km across slammed into the Earth with the force of 1.8 million Hiroshima bombs, leaving a 24 kilometer wide crater in its wake.
Nordlingen has an intact medieval city wall, complete with 5 city gates. You can walk on the city wall for free; it will take you about 1.5 hours to circle the town on the wall.
One of the most noteworthy aspect is the city wall which is complete and accessible to tourists.
One can climb up to the wall from one of many guard towers and walk around the whole town.
Such a journey takes a little longer than an hour. During that walk you can take a look at the Nördlingen church in the middle of the town from every direction.
St. George’s church is a really prominent structure because its tower, called Daniel, is 90 meters high. It was built in the 13th century. What is the most fascinating aspect about this church is the material that was used to build it. It is an impact breccia called suevite.
This hill is actually the rim of the crater
What is left of the impact structure now is a circular depression about 150 meters deep and 24 kilometers wide. Nördlingen is just in the middle of that structure. The depression was originally thought to be volcanic in origin until one of the founding fathers of impact geology Eugene Shoemaker visited Nördlingen and noticed that the church in the middle of the town in not only notable because of its old age but also because it is built of a very unusual and rare rock type which is always associated with large impact events. Shoemaker published his finds in 1961.
As if it isn’t already exciting enough, there is one more interesting aspect about the rocks that are so widely used to build houses in Nördlingen. The rocks that were hit by the meteorite contained graphite (graphite-bearing gneiss) which was turned into diamonds by the immense pressure (60 GPa) exerted by the impact explosion. These diamonds are microscopic (up to 0.3 mm) and have therefore no value as gemstones. However, there are trillions of them. Their estimated total mass is more than 70,000 tons (concentration in rocks reaches 0.7 ppm which is 0.7 grams per one ton of rocks). Hence, the houses in Nördlingen are built from diamonds and impact glass and breccia. I wonder whether people anywhere else in the world have such a noble taste for building materials.