Castra.

This is coolbert:

Not since the year 1617?

Severe drought Europe, rivers drying up. Exposed objects normally underwater the military dimension.

1. "Low water levels on Danube reveal sunken WW2 German warships"

From www.reuters.com the story by Fedja Grulovic.

"PRAHOVO, Serbia, Aug 19 (Reuters) - Europe's worst drought in years has pushed the mighty river Danube to one of its lowest levels in almost a century, exposing the hulks of dozens of explosives-laden German warships sunk during World War Two near Serbia's river port town of Prahovo."

"The vessels were among hundreds scuttled along the Danube by Nazi Germany's Black Sea fleet in 1944 as they retreated from advancing Soviet forces, and still hamper river traffic during low water levels."

GO SEE THE EMBEDDED SLIDE SHOW. THOSE WARSHIPS HAZARDOUS TOO IN THE SENSE THEY PROBABLY CONTAIN QUANTITIES OF UNEXPLODED ORDNANCE.

2. "Hitler's Scuttled Black Sea Fleet, Centuries-Old 'Hunger Stones' Emerge From Dry Riverbeds In Drought-Stricken Europe"

"Extreme droughts across Europe are revealing thousands of years of lost history."

See the image! Awesome! Roman camp [castra] the outline still visible. River bed having dried up during the drought a military object from antiquity exposed as almost never. Click on image to see an enlarged view.

Devoted readers to the blog please recall that year 1617 one year prior to the start of the Thirty Years War! Drought and crop failure [?] exacerbating an existing political situation already unstable perhaps a contributing factor that led to the beginning of the war? I cannot find any mention on the Internet of such a correlation.

coolbert.