After the brief, initial period of surprise, the Germans launched a brutal pacification of the uprising.
Searching for centres of resistance and those who had gone into hiding, they systematically combed street after street and tenement house after tenement house, leaving behind them the bodies of civilians and the charred remains of buildings. They referred to the people who jumped from the balconies and windows of burning houses as “paratroopers”. In the following days, the fighting focused on individual buildings and even bunkers. On 8 May, the Germans discovered a shelter at No. 18 Miła Street which housed the headquarters of the Jewish Combat Organization. Tragically, the organization’s commander, Mordechaj Anielewicz, was present inside. He was not taken alive, however the exact circumstances of his death remain unknown. Some of his comrades died of gas discharged by the Germans into the bunker, while others committed suicide; a handful managed to escape.
Archaeological excavations commenced on 6 June 2022 and lasted until 19 August 2022. The objective was to examine the relics of the old tenement houses located in the immediate vicinity of the bunker at No. 18 Miła Street. It was assumed that if the structure actually extended under the three adjacent buildings, at least some of its elements should be visible outside the area of the contemporary place of memory. The exact area of research was determined on the basis of the results of electrical resistivity tomography (which indicates potential empty spaces or loosened underground fill). The remains of the cellars were reached already on the first day. Their state of preservation suggested that the entire station may be well preserved and practically intact (post-war interventions were in essence limited to the surface layers). Accordingly, the decision was made to abandon the anticipated second cut and instead focus on the area already exposed. It was determined that the uncovered remains of the cellars belonged to two tenement houses located at the pre-war addresses of No. 39 Muranowska Street and No. 41 Muranowska Street. These tenements had been built in the 19th century on the very same premises that along Miła Street, running in parallel, had the numbers 18 and 20. In the inter-war period, both lots were home to tenement houses typical of the Warsaw of the era, with internal courtyards, annexes, and two entrance gates (one in Miła Street and the other in Muranowska Street).
Furthermore, throughout the 1930s – right until the outbreak of the war – each property had one and the same proprietor. The building at No. 18 Miła Street – No. 39 Muranowska Street belonged to Zysla (Zysia) Wejnberg, while the house at No. 20 Miła Street – No. 41 Muranowska Street was owned by Icek Majer Blass. Numerous movable historical artefacts were found in the uncovered cellars, including various objects associated with the everyday and religious lives of residents, as well apartment furnishings and fittings. An analysis of these artefacts indicates that the buildings were inhabited on the whole by representatives of the middle class. This is evidenced by the discoveries made in one of the cellars at No. 39 Muranowska Street. Clearly, these indicate that the brick basement walls had been covered with a layer of plaster, upon which a decoration was then painted. In this room there were also books – mainly Hebrew-language religious literature, although a novel in Polish was also identified. All of them were burned – some in full, some in part – and the floor of the room was covered with ash and smouldered pages. A single small candlestick, a cup for the ritual washing of hands – the netilat yadayim – and a pair of tefillins (six-sided leather boxes containing fragments of the Torah and fitted with long straps; during prayer, one box is fastened to the forehead, and the other to the left arm) were also discovered in the same room. One of the larger finds was a metal sink that had once been connected to the water system and probably served some religious function.
Perhaps the basement was a place of prayer, or even a formal prayer house. Such cellar houses of prayer had in fact existed, for example in Będzin, where a similar facility has survived to the present day. No traces of a smugglers’ hideout were found in the basements at No. 18 Miła Street – No. 39 Muranowska Street 39, however in the course of research conducted at No. 20 Miła Street – No. 41 Muranowska Street it was discovered that the basement infrastructure had been deliberately reconstructed, and concrete block walls added. They formed a room that was covered with a concrete ceiling and equipped with pipes (perhaps water pipes) and an electric cable. The exit from it led to a corridor that had been created by building new elements on to the older structures. The construction of these walls made it possible to form both a hallway and a narrow entrance to the concrete room. The corridor itself leads west, where it connects with a second corridor running straight to the south, directly towards the present-day place of memory which surrounds the Anielewicz Mound. Everything indicates, therefore, that what was found were traces of a basement communications route which connected the series of basements at Miła Street with the cellars at Muranowska Street.
Basing on these findings, a hypothesis was developed that the reconstructed fragments formed part of an extensive basement hiding place, commonly referred to as Anielewicz’s bunker.