Experts of the Archaeological Survey of India (ASI) have taken up chemical cleaning of the Raja Rajan Gopuram at the entrance of the Big Temple at Thanjavur. The 1000th year of construction of the temple is to be celebrated before June, 2010. The Kumbhabhishekam is also due for the temple. In view of these events, the ASI has taken up chemical cleaning of the gopurams and vimanas of the temple. Keralandhagan Gopuram, the first gopuram at the entrance of the temple has already been cleaned by the ASI experts.

Now the second gopuram called Raja Rajan Gopuram has been taken up. The 212 ft all-stone Vimana of the temple on the sanctum sanctorum will be cleaned subsequently. The Thanjavur Big temple, built by Raja Raja Cholan is an architectural marvel and is one of the world heritage monuments.

The other two all-stone temples similar to that of the Big Temple have been declared as world heritage monuments by the UNESCO. They are the Iravatheeswaraswamy temple at Darasuram and the Big Temple at Gangai Konda Cholapuram. Thirubuvanam Temple is also constructed on these lines by the Chola kings. Growth of moss and lichens on the stone structure is cleaned periodically by the ASI experts using chemicals.