13/15 Długa Street. The Military Cathedral.
In the year 1642 a small wooden church of Piarist Friars was built in this place. In the year 1701 a new stone church was finally built.
During the Warsaw Uprising at the area of the church an insurgent field hospital was situated.
In the side chapel the troops from the Old Town and the New Town would swear an oath here before going to the action.
In front of the Military Cathedral the one and only official march of the insurgent troops happened on August 6, 1944. On August 20, 1944 the church was bombed.
It was rebuilt in the years 1946-1960.

The gates of bronze lead us to the Cathedral. The most important battle scenes from the history of Poland are put on the gates. One fragment is dedicated to the Warsaw Uprising 1944.
On the inner gates there are various images of the Holy Mary put, among of which there is also the Holy Mary of the Home Army.

On the outer church wall one can see the following plaques:
- in memory of lieutenant colonel Fr. Prelate Wacław Karłowicz a.ka. "Andrzej Bobola", the chaplain of the Home Army battalions "Gustaw" and "Antoni", the founder of the field hospital that was placed here;
- commemorating 430 people who were murdered by Germans in the insurgent hospital on September 1, 1944.

In the right-hand cloistered of the church one can see the Katyń Chapel. On the chapel altar there is the painting of the Holy Mary of Katyń and on its walls there are 15.000 plates with the names of casualties of NKWD (the Soviet secret police) from Katyń, Charków and Miednoje as well as 7.000 nameless plates.

In the left-hand cloistered, among the others, there are plaques dedicated to the Warsaw Uprising 1944:
- commemorating the soldiers of the troop "Barry" of the Home Army unit "Sosna", who had a post here from August 7 till August 20, 1944, the day when the church was bombed;
- commemorating the soldiers of the Home Army battalion "Nałęcz";
- commemorating the soldiers of the Home Army Motor Artillery Wing who fell in either conspiracy or the Warsaw Uprising;
- commemorating the Polish aviators fallen and murdered, who fought on all the fronts of WW II and the Home Army units of the Air Base Łużyce-Warszawa;
- commemorating the girl guides and boy scouts of the "Grey Regiments" - the Home Army soldiers fallen in the fight of Poland;
- in memory of military chaplains fallen and murdered inter alia in the Warsaw Uprising;
- commemorating the soldiers of insurgent sanitary service as thanksgiving for their bravery and devotion;
- in memory of co-originators and commanders of the Grey Regiments;
- in memory of Stefan Korboński, the co-originator of the Polish Underground State;
- in memory of Major Lucjan Giżyński a.k.a. "Gozdawa", the commander of sub-line segment "Gozdawa" in the unit "Sosna" in the Old Town;
- in honour of cavalry captain Witold Pilecki, the hero of the 20th century;
- in memory of the minesweeper captain Marek Szymański a.k.a. "Czarny" from the Warsaw company of the 27th Home Army Wołyń division in the battalion "Czata 49" of the unit "Radosław";
- in memory of second lieutenant Robert Jan Rachmielowski a.k.a. "Rob" from the battalion "Czata 49" of the Home Army unit "Radosław", who fell on September 1, 1944;
- in memory of second lieutenant Stanisław Srzednicki a.k.a. "Stach", the commander of the company "Orlęta" of the battalion "Gozdawa" from the Home Army unit "Sosna" as well as corporal officer cadet Zygmunt Elgas a.k.a. "Cień", the platoon commander in the company "Orlęta", who both fell in the Warsaw Uprising;
- in memory of Eileen Frances Short-Garlińska, the Irish woman who chose to be the Polish woman, the Home Army soldier, the translator in the Government Delegation for Poland, the nurse in the Warsaw Uprising.