Original sentence: The inner sanctum sanctorum is more than 3500 years old, and the outer walls and external construction are about 1500-2000 years old
Edited sentence: Almost at the time when all other civilizations used to live in caves like animals and hunt for their food and wear animal skins.It is the greatness of the Tamil Race that  they have the foresight and the ability to make this construction when humans across the world [ most of them did not know how to live ].The inner sanctum sanctorum is more than 3500 years old ...  and the outer walls and the outer construction is about 1500-2000 years