Sena patriarch Mr Thackeray was cremated on Sunday at the Shivaji Park, the same ground from where he had launched his party 46 years ago.
The sprawling ground already has a memorial dedicated to Maratha warrior king Chhatrapati Shivaji Maharaj.
"We want his (Thackeray's) memorial to be built here (Shivaji Park). The party wants his memorial next to Chhattrapati Shivaji's memorial. Why won't the government permit it," Mr Joshi asked.