Legend has it that the Sri.Padmanabaswany Temple,Tiruvananthapuram,India has treasures in the cellars and this is proved to be correct when the cellars were opened couple of days back under the orders of the Supreme Court,
The value of the treasure is estimated to be around Rs.50,000 Crores and counting is still on.
There are many temples in the South about which treasure legends abound.

1.Srivilliputhur.It is believed that a tunnel exists linking Sri Andal Temple Srivilliputhur, the Second Holy place for Vaishnavas,next to Sri Rangam, to Madurai,
Sri Krishna Devaraya is reported to have built it.
Thirumalai Naicker(of Thirumala naiker Mahal Fame) is also said to have built 48 structures,with bell Towers so that he could have his meals in Madurai,after the Naivedyam or offering to God, by having the bells in the structure tolled the moment the offering is over.
Rani Mangamma of Madurai is said to have offered priceless gems to the Temple.
Some of these structures still remain.
The approximate distance between Madurai and Srivilliputhur is 48 miles.
The tunnel is rumored to contain vaults which contain treasure trove.
2.Palani.

A Treasure is supposed to exist beneath the sanctum sanctorum of Bogar, a Siddha who has consecrated the Deity, Lord Dandayudhapani.
Might be worth the while to check on these places as well.
Story:
Kerala has stumbled upon a treasure trove in the underground chambers of the centuries-old SreePadmanabhaswamy Temple here, where a Supreme Court appointed panel prepared the inventory of the priceless heap of precious metals.
The value of articles stocked in the vaults of the temple, managed by the royal family of the erstwhile Travancore princely state, would run into thousands of crores of rupees. Unofficial sources associated with the ongoing examination of the temple cellars pegged the jackpot at Rs 50,000 crore.
http://www.expressindia.com/latest-news/Kerala-temple-treasure-could-be-worth-50K-crore/811753/