a wooden fence, later replaced by a concrete wall. Railway buildings and installations on the site, as well as a former homeless shelter and a hospital were converted into a prisoner selection facility. The rest of the train station served its normal function for the rest of the city during the deportations. The railway leading to the square was originally constructed in 1876, as a side rail to the city's main line. Warehouses and other buildings were built between 1921 and 1935. After the German invasion of Poland in September 1939, and the occupation of the country, the square came under the administration of a dedicated German institution, the Transferstelle ("Transfer Bureau"). Originally its purpose was to oversee the flow of goods between the newly established Warsaw Ghetto and the "Aryan Side" of Warsaw. At the time the ghetto's inhabitants referred to the square as "Umschlag". At the end of January 1942, the southern portion of the square was incorporated into the ghetto. Deportations to Treblinka Starting in July 1942 the buildings located around the square began to be used by the Germans as places of selection. Jews were gathered and held there before deportation to the Treblinka death camp. The headquarters of the SS units responsible for the selections and deportations were located in the building of the old elementary school on Stawki Street. The Umschlagplatz was divided into two parts. The southern part, which was located within the walled ghetto, was the gathering point where those destined for transport awaited the arrival of the trains. The northern part included the rail and station where people were physically loaded onto the trains for Treblinka. Initially, the roundups for the Umschlagplatz were supervised by the Jewish Ghetto Police. Houses or entire blocks were cordoned off and then all the inhabitants were forced to gather in a controlled spot, such as a closed off street or a tenement's courtyard. After a check of documents, the individuals were forced, under escort, to proceed to the Umschlagplatz. Emptied buildings were searched and those found hiding were either killed on the spot or joined with those proceeding to the square. Some young men were moved to the so-called Dulag, a temporary internment camp, from which some were sent to labor camps rather than death camps. The order in which the ghetto's blocks were emptied was organized by the Germans. Beginning in August, German-run workhouses