The Tannenberg Memorial was a monument to the German soldiers of the Battle of Tannenberg and the First Battle of the Masurian Lakes during World War I, as well as the medieval Battle of Tannenberg of 1410. The victorious German commander Generalfeldmarschall Paul von Hindenburg became a national hero and was later interred at the site.
Dedicated by Hindenburg in 1924, on the tenth anniversary of the Battle of Tannenberg near Hohenstein, the structure, which was financed by donations, was built by the architects Johannes and Walter Krüger of Berlin, and completed in 1927. The octagonal layout with eight towers, each 20 metres high, was influenced by Holy Roman Emperor Frederick II's Castel del Monte and Stonehenge.
Wikipedia https://en.wikipedia.org/wiki/Tannenberg_Memorial
Address 11-015, Poland
Coordinates 53°34'52.666" N 20°15'38.71" E