boingo, New Delhi is totally separate from Delhi even though they are adjacent. It is possible that AR13 went to New Delhi, but the traditional India is on display in Delhi while New Delhi is more of a modern commercial city. As best I can tell, the visit of AR1, episode 7 was the only one previously to Delhi or New Delhi. AR1 teams (except for Frank and Margarita who went directly to the pitstop with the Fast Forward) landed at Indira Gandhi International Airport, definitely in New Delhi. Then they went to Old Delhi to visit a market. Next they went ot the Red Fort(still in Delhi), where the Chandi Chowk market is where they got their next clue, a statue of the Taj Mahal. This episode ended in Agra. Other visits to India by Amazing Races were:
AR4 Mumbai, Aleppy
AR5 Calcutta
AR7 Lucknow, Jodhpur
AR10 Chennai