The Prussian Eastern Railway was the railway in the eastern Kingdom of Prussia until 1918. Its main route, approximately long, connected the capital, Berlin with the cities of Danzig (Gdansk) and Königsberg (Kaliningrad). At Eydtkuhnen (Chernyshevskoye) it reached the German Empire's border with the Russian Empire. The first part of the line opened in 1851, reaching Eydtkuhnen in 1860. By March 1880 the total route length reached , with a main parallel route in the south via Bromberg (Bydgoszcz) and Thorn (Torun) to Insterburg (Chernyakhovsk). The lines were the first part of the later Prussian State Railways .