![D" Block "dark cell" entrance at Alcatraz Prison, used for solitary confinement, known as the Special Treatment Unit (S.T.U.). Stock-Foto | Adobe Stock D" Block "dark cell" entrance at Alcatraz Prison, used for solitary confinement, known as the Special Treatment Unit (S.T.U.). Stock-Foto | Adobe Stock](https://as1.ftcdn.net/v2/jpg/04/68/21/62/1000_F_468216234_frtAti1aM0w1TeeNoTrF5uPSofx0s2g4.jpg)
D" Block "dark cell" entrance at Alcatraz Prison, used for solitary confinement, known as the Special Treatment Unit (S.T.U.). Stock-Foto | Adobe Stock
![Alcatraz D Block Cellhouse San Francisco Kalifornien Stockfoto und mehr Bilder von Gefängnis - iStock Alcatraz D Block Cellhouse San Francisco Kalifornien Stockfoto und mehr Bilder von Gefängnis - iStock](https://media.istockphoto.com/id/1499476662/photo/panoramic-view-of-the-maximum-security-block-and-module-and-punishment-cells-of-the-alcatraz.jpg?s=612x612&w=is&k=20&c=ToJ2ObK8IV6VtO6IGF0huYw3PhDR1iY-jDkK2MkJ228=)
Alcatraz D Block Cellhouse San Francisco Kalifornien Stockfoto und mehr Bilder von Gefängnis - iStock
![File:Two men standing in the newly completed Alcatraz cell block D, March 20, 1911.jpg - Wikimedia Commons File:Two men standing in the newly completed Alcatraz cell block D, March 20, 1911.jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/6/6c/Two_men_standing_in_the_newly_completed_Alcatraz_cell_block_D%2C_March_20%2C_1911.jpg)