The world's three big blue cities, Greece Santorini, Morocco Shefshavan, today came to India's blue city Jodhpur, eyes can see, all blue. It is said that the house was painted blue to prevent mosquitoes and insects, another saying that blue was one of the ways to show identity at the time, and after the caste system was abolished, people painted their houses blue. The houses on both sides of the street, regardless of size, rich and poor, are painted blue, reflecting the blue of the sky above the head, and the house also presents different light blue, sky blue, water blue, deep blue, and blue.