While four of these structures got the prestigious tag last year, seven others were included as world heritage property through a notification last month. Officials say this is the first-ever expansion of a world heritage site.

"This expansion doesn't count towards two permitted annual nominations. Last year, Nalanda and Kanchenjunga were nominated for world heritage inscription; the Humayun's Tomb boundary modification proposal has submitted this February. All the submitted nominations have been inscribed on the world heritage list, making it a momentous year for Indian heritage," said an official.

In 2015, one the request of Aga Khan Trust for Culture and Archaeological Survey of India, UNESCO included Isa Khan's Tomb, Bu Halima's Tomb and Garden, Afsarwala Garden Tomb and Arab Serai Bazaar as part of the world heritage site. In early this year, AKTC proposed further boundary modification, which was forwarded by the Centre to UNESCO.

"Seven other 16th-century garden tombs have been included. These are Lakkarwala Burj, Sunder Burj, Sunderwala Mahal, Mirza Muzzafar Hussain's Tomb, Chotte Batashewala Mahal, an unknown Mughal tomb and Nila Gumbad," said an official