The city is famous for the capital of the Mughal emperors from 1526 to 1658 and maintains a major tourist destination because of its many marvelous Mughal-era buildings such as TÄ j Mahal , Agra Fort and FatehpÅ `` r SikrÄ `` , all three of which are selected as UNESCO World Heritage Sites . TÄ j Mahal , Agra Fort and FatehpÅ `` r SikrÄ `` , all three of which are UNESCO World Heritage Sites .