What is Tegel Prison, the Gestapo Prison, Buchenwald?

After his eventual arrest for participation in the conspiracy to kill Hitler, Bonhoeffer was taken to Tegel Prison and there interned for eighteen months. While there, he maintained a correspondence with his fiancée, Maria von Wedemeyer, and was able to maintain communications with his allies in the ongoing effort to topple the Nazis. Bonhoeffer was also imprisoned, for a time, in a Gestapo prison in Berlin, and was eventually taken to Buchenwald, one of the largest Nazi concentration camps where he spent two months.