On the western part opposite to the main entrance is the famous or rather we should say infamous Black Hole of Calcutta Monument. This was not the original place of the monument well for that matter this is not the original monument in the first place also. A memorial was built by John Holwell at the site of the black hole where is was said that Siraj–ud–Daulah had taken 146 prisoners and locked them overnight in 14 feet by 8 feet cell. Due to the heat and cramped up space, only 23 had survived and John Holwell was one of them. He later became the governor of Bengal are erected a monument at the spot of the original (debated) black hole of Calcutta. This was right next to the present day GPO.

For some reason, this monument had vanished from the face of the earth in 1822 and was somehow brought back to public view by Lord Curzon in the year 1901 at a new spot located between Writer’s Building and GPO on the north-western section. This again became a point of contention during the freedom movement of the 1940’s so as a compromise it was shifted inside the compound of St. John’s Church.
The monument has names of all the victims but these are also debated since names of not all of them were recorded thus it was collected from memory and later additions from multiple sources.