Security has been tightened at historical monuments in Agra, particularly the Taj Mahal, following the serial blasts in New Delhi, police said on Monday.

Years after being threatened by the effluent gases of the Mathura oil refinery, the white marble of the Taj Mahal faces another threat - a proposed garbage dump nearby will release methane and other gases.

A group of Shiv Sena activists on Thursday managed to sneak into the Taj Mahal and performed 'aarti' and puja inside the precincts. They have been taken into custody.

The splendour of Mughal architecture - its mosques, tombs and other structures - is in danger of being lost to neglect and pillage of time but an American university has taken up the task of documentation of neglected Islamic monuments in India.