A 40 kg block of red sandstone fell off Saheli Burj at the Taj Mahal, close to the entrance. No one was hurt, officials said.
Bhuvan Vikram, superintending archaeologist of the Archaeological Survey of India (ASI), blamed the Wednesday mishap on monkeys. He said a plan was being drawn up to contain the simian nuisance.
The 17th century Taj is India's biggest tourist draw.
