Kala Tazia Juloos largest gathering of shia Muslim's mourn ( Delhi 2022 

This procession is the last procession of Muharram, which is done by Shia Muslims, who commomorate in the memory of Imam Hussain, this procession is about 16 km long.
It is a walking procession, about 1 to 200000 people gather in this procession and it is a religious procession.