subcamps (BIIa–BIIf) with their own gates and fences. The first two sectors were completed (sector BI was initially a quarantine camp), but the construction of BIII began in 1943 and stopped in April 1944, and the plan for BIV was abandoned. SS-Sturmbannführer Karl Bischoff, an architect, was the chief of construction. Based on an initial budget of RM 8.9 million, his plans called for each barracks to hold 550 prisoners, but he later changed this to 744 per barracks, which meant the camp could hold 125,000, rather than 97,000. There were 174 barracks, each measuring , divided into 62 bays of . The bays were divided into "roosts", initially for three inmates and later for four. With personal space of to sleep and place whatever belongings they had, inmates were deprived, Robert-Jan van Pelt wrote, "of the minimum space needed to exist". The prisoners were forced to live in the barracks as they were building them; in addition to working, they faced long roll calls at night. As a result, most prisoners in BIb (the men's camp) in the early months died of hypothermia, starvation or exhaustion within a few weeks. Some 10,000 Soviet prisoners of war arrived at Auschwitz I between 7 and 25 October 1941, but by 1 March 1942 only 945 were still registered; they were transferred to Auschwitz II, where most of them had died by May. Crematoria II–V The first gas chamber at Auschwitz II was operational by March 1942. On or around 20 March, a transport of Polish Jews sent by the Gestapo from Silesia and Zagłębie Dąbrowskie was taken straight from the Oświęcim freight station to the Auschwitz II gas chamber, then buried in a nearby meadow. The gas chamber was located in what prisoners called the "little red house" (known as bunker 1 by the SS), a brick cottage that had been turned into a gassing facility; the windows had been bricked up and its four rooms converted into two insulated rooms, the doors of which said "Zur Desinfektion" ("to disinfection"). A second brick cottage, the "little white house" or bunker 2, was converted and operational by June 1942. When Himmler visited the camp on 17 and 18 July 1942, he was given a demonstration of a selection of Dutch Jews, a mass-murder in a gas chamber in bunker 2, and a tour of the building site of Auschwitz III, the new