Those arrested last night included C Senthil Kumar, son of AIADMK leader Chellathurai, the main accused in the case and his son-in-law M Senthil Kumar.
Police said Chellathurai was absconding and they had launched a hunt to nab him.
The building suffered damage while demolishing an adjacent building near the famous Sri Meenakshi Temple two days back, over which Chelladurai claims ownership.
The heritage building houses some government offices, including that of the Public Works Department. One dome of the building and pillars had been completely damaged.
The official said they were verifying the records as there was no possibility for individual holding near the Palace.
Cases were registered under various sections of IPC including rioting and causing damage.