Burg Boyneburg

Sontra, Germany, Germany

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Burg Boyneburg, near Sontra in Germany's Ringgau region, is the ruin of a once-mighty 11th-century summit castle likely built by the powerful Counts of Northeim on a 513-meter limestone peak to protect their estates.

First documented in 1107 and reverting to imperial control after the Northeim line died out in 1144, it became a Reichsfeste where Emperor Frederick Barbarossa issued privileges in 1156 and consecrated a chapel in 1188. 

The expansive 4.5-hectare fortress, with its pentagonal bergfried tower, double moats, and walls, was torched by Croatian troops in 1637 during the Thirty Years' War, briefly repaired, then abandoned by 1672 and quarried for local stone, leaving today just two 25-meter tower walls, a reconstructed 1950s gatehouse, and earthworks as a popular hiking spot.