The Upper Prison complex and stockade wall entrance in 1902. Within the perimeter there were four prison complexes.

Military inmates during a routine verification count in 1902. The count is being performed on the Upper Prison Stockade grounds, facing one of the prison buildings. Note the sentry patrolling the catwalk that encircled the prison boundaries.

The only known photograph of the interior of the Upper Prison, circa 1902. The Upper Prison complexes could accommodate 307 prisoners in total, with two-tiered cellblocks. Close examination of this damaged photograph reveals several cells containing family pictures, and a stairwell with no safety railings.

In April of 1900, Alcatraz was temporarily used as a makeshift health resort for soldiers returning from the Philippine Islands with tropical contagious diseases. Many of these men had returned with severe dysentery and they were initially sent to the General Hospital at the Presidio. While convalescing, the men were actually organized into military companies and “Convalescent Company Number Two” was sent to Alcatraz.

As the prison population had continued to grow at Alcatraz, a temporary wooden cellhouse had been constructed on the parade ground. The cells in the wooden prison were small enclosures with the appearance of horse stables. There were 113 cells, and the average airspace per man was only 161 cubic feet. The cells had an average size of 8 ¹/ ₄x 6 x 3 ¹/ ₄feet, only a little larger than a standard closet. Even by the standards of that era, the wooden cellhouse was considered inadequate and unsafe for housing a large prison population. A medical report of the era described the following conditions:

Sanitary defects of the prison are especially apparent. The ventilation of the buildings is very faulty. The corridors, kitchen, and mess rooms are disagreeably drafty... The prisoner when locked up for the night is virtually boxed in for so many hours... The means available for solitary confinement are such as have long been discarded in the better class of civilian penal establishments.

In 1902, a lantern fire inside the wooden prison almost turned catastrophic. A quick-thinking guard immediately smothered the fire using water and sand, but the inmates remained horrified of the potential dangers. They knew that if another fire should start, they would be trapped inside a wooden inferno and feared being burned alive.

By 1904, inmate labor had been harnessed to modernize the prison at Alcatraz. The inmate population was moved to the upper prison, which now had the capacity to safely accommodate 307 men and the lower prison was converted to a work area for inmates, housing the laundry and other small workshops. By 1905 the inmate population had grown to over 270 inmates, and convict labor was being used to demolish several of the old building structures and begin new construction. In April of 1906, following the catastrophic San Francisco earthquake which completely destroyed the city’s jail facilities, 176 civilian prisoners were temporarily transferred to the island for safe confinement.

Army prisoners seen working in the Upper Prison against the stockade wall, breaking rock into gravel in 1910.

Another 1910 photograph showing army prisoners breaking rock with small hammers, while kept under close guard by an armed sentry. This view is looking east toward the future site of the powerhouse.

A rare photograph of garrison soldiers congregating at the island dock, taken on August 12, 1904. One of the Upper Prison buildings is partially visible at the top left.

A panoramic photograph showing the massive fires and destruction that followed the San Francisco Earthquake of 1906.

Alcatraz in 1907.

A 1910 photograph of the Alcatraz Morgue. The Morgue was not used during the years in which the island served as a Federal penitentiary.

U.S. Disciplinary Barracks

On March 21, 1907, Alcatraz was officially designated as the Pacific Branch of the United States Military Prison, and the Third and Fourth Companies of the U.S. Military Prison Guard were established there as a permanent garrison. Trained sentries would supervise all prisoner activities, and it was during this period that the rigid routine of Alcatraz would begin to emerge. By the turn of the century, the military prison on the island had grown so large that it obscured the lighthouse. Work on a new lighthouse began in 1909 and soon the tower would soar into the sky at a height of eighty-four feet. Electricity powered the light, as well as the fog sirens at the north and south ends of the island. The new keeper’s house was adjacent to the quarters of the Warden and prison doctor, located at the top of the main roadway.

The original lighthouse would be replaced in 1909 by an eighty-four-foot concrete tower, which loomed over the newer concrete prison. This photograph shows the new lighthouse under construction.

In 1909 Major Reuben Turner, a military construction engineer from the 29 ^thInfantry, designed and supervised an ambitious building project. He created a fully enclosed building that incorporated the main prison, hospital, kitchen, mess hall, library, shower rooms and auditorium – all encapsulated within a single cement superstructure. The top floors of the old Citadel were destroyed and a large new cellhouse was constructed, literally on top of the solid masonry structure of the old defensive barracks. The cellhouse was the largest steel-reinforced concrete structure in the world at the time of its construction, and it was designed to hold up to six hundred inmates. Each inmate could occupy a private cell, with a forced air ventilation system and cold running water. A convict labor force with a meager $250,000 budget would be tasked to build the entire cement complex, which would be completed in 1912. By the late 1920’s the three-story structure was nearly at full capacity.

The original prison blueprints by Major Reuben Turner, a military construction engineer from the 29th Infantry. Turner’s escape-proof design featured a fully enclosed building that incorporated the main prison, hospital, kitchen, mess hall, library, shower rooms and auditorium – all encapsulated within a single steel-reinforced cement superstructure.

Construction photographs of the main prison taken in roughly 1909-1910.