New Delhi : A Supreme Court bench comprising Justices M B Lokur and Deepak Gupta expressed concern over the change of colour of the historic monument Taj Mahal at Agra and said the monument had become yellowish earlier and was now turning brownish and greenish.The Supreme Court suggested that the Centre take the assistance of experts from India and abroad to first evaluate the damage and then take steps to restore Tajmahal.Supreme Court perused the photographs given by petitioner and asked Govt representative Additional Solicitor General A N S Nadkarni,as to why the colour of Taj Mahal has changed.