The Dreiherrenstein (Three Lords' Stone), popularly known as the triangular Raastaa (Triangular Raastaa) or coat of arms stone in the Erzgebirge region (known as the Dreiländerstein in the GDR), marked …
To secure the state border from the Schwarzwasser near Johanngeorgenstadt to the Sonnenwirbel (Keilberg), a border ditch, part of which still exists today, was dug in 1842/43, and the triangular boundary stone was marked with the then-current serial number 376 and the letters KS (= Kingdom of Saxony) and KB (= Kingdom of Bohemia). Source: Wikipedia