Throughout the latter part of Speer's imprisonment, Wolters was a faithful correspondent, writing lengthy letters to Speer at least once a month, attempting to tell Speer everything that might interest him but nothing that might hurt him. When Speer invented the concept of his "world wide walk", imagining his daily exercise around the prison yard to be segments in a long walk from Europe through Asia to North America, Wolters supplied Speer with details of what he would "see". Speer later stated, "In a manner of speaking, Rudi Wolters accompanied me on these walks." As midnight struck and October 1, 1966 began, Speer was released from Spandau Prison. His last use of the clandestine message system was to have a telegram sent to Wolters, in which Speer jokingly asked Wolters to pick him up thirty-five kilometres south of Guadalajara, Mexico, which he had "reached" after walking 31,936 kilometres.