Church of John of God

In 1650, within his ancestral village of Leszno near Warsaw, Bogusław Leszczyński established a church and monastery known as the Bonifratrów, or the Brothers Hospitallers. The inaugural prior of the monastery was Father Modest Genoino, a respected Neapolitan priest and renowned surgeon in Warsaw. The inception was modest, and the site was situated quite a distance from the city center. The endeavor received support from the Morsztyn brothers: Tobiasz Morsztyn, a clerk to the Crown, and Jan Andrzej Morsztyn, a poet and Royal secretary.

Recognizing the remote location of the church and monastery from Warsaw's center, funds were provided to facilitate their relocation. A parcel of land on Wielopole was bestowed to Tobiasz Morsztyn by Jan Wielopolski, and within this vicinity, Jan Andrzej Morsztyn erected the Saxon Palace, now known as Piłsudski Square.

The construction of the new church and convent reached completion in 1673.

In 1713, Augustus II the Strong acquired Morsztyn's palace for his residence and expanded it to encompass neighboring areas, including the monastery and church. Consequently, resources were allocated for the construction of a new church on the present site. Construction commenced in 1728, and a few years later, the Bishop of Poznań, Jan Joachim Tarło, consecrated the church and monastery.

Alongside the church, a hospital was also established, initially with a mere 8 beds. In 1760, Prince August Aleksander Czartoryski, voivode of the Ruthenian province, commissioned a new facility accommodating 34 patients and several auxiliary rooms. Architect Jakub Fontana, the church's builder, allocated 74,000 złoty in his will dated March 20, 1773, for the maintenance of the institution and the aid of the sick. This provision was ratified by a parliamentary delegation in 1775.

Initially, the brothers not only served as priests and sacristans but also included a chaplain who fulfilled priestly duties. Over time, their focus shifted towards medical and merciful endeavors. Paschal Stirzelheimer, a former provincial of Poland, obtained a medical doctorate in Zamość.

During the period of annexation, the Brothers Hospitallers suffered repercussions from the tsarist authorities due to their assistance to insurgents in 1831 and 1863.

Amid the Warsaw Uprising, the church, hospital, and monastic structures became pivotal points in the insurgents' resistance. These sites were defended by battalions including Zośka, Parasol, and Watch 49 until August 25, 1944, although the buildings suffered considerable damage during these conflicts.

Subsequent to the war, the church was reconstructed, while the hospital was not. Inside the church, few monuments remain, notably a seventeenth-century depiction of Saint Andrew near the altar and an image of the Virgin Mary on the altar. The premises are adorned with a range of memorials, some dedicated to the memory of the Home Army and Father Serafin Kloc, who facilitated and supported the church's restoration.