patlini, that was true before 1947 when the partition of the primarily Hindu parts into India and the primarily Islamic parts into Pakistan happened. Since then there are not very many mosques in India.  I might have seen one or two in travelling between or in most of the major urban areas. Here is a list of what it purported to be all 16 mosques in India(a trivial number for a country of 1 billion population) including two mozques in Delhi(which don't match):
Jama Masjid  India Delhi 1656 
Mecca Masjid  India Hyderabad 1694   
Moti Masjid  India Delhi 1660  
Sidi Saiyyed mosque  India Ahmedabad 1573   
Mubarak Mosque  India Qadian 1883  
Hazratbal Shrine  India Srinagar  
Jama Masjid  India Srinagar 1400  
Cheraman Juma Masjid  India Kodungallur 629  oldest mosque of India, second oldest Juma Masjid of the world. 
Malik Dinar Mosque  India Kodungalloor    
Jama Masjid  India Kalbadevi (Mumbai) 1802   
Haji Ali Dargah  India Worli (Mumbai) 1631  
Babri Mosque  India Ayodhya 1528 – destroyed on December, 6th 1992 
Sir Syed Masjid  India Aligarh    
Masjid-ul-Jamiah  India Tamilnadu   
Adina Mosque  India Firozabad (West Bengal) 1373   
Cheraman Juma Masjid  India Kerala 629   
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Categories: Mosques in India | Lists of Islamic buildings and structures