The palace at Fatehpur Sikri is a UNESCO World Heritage Site. It's a prime example of Indian excellence. Its style is as crazy as the emperor who commissioned it. Emperor Akbar was known to play life size chess in the courtyard, using naked women from his harem as pawns...
I suggest you take your time when visiting it, so that you can fully appreciate the rich detailing on its facades. From the top of this hill, you get a great view of the beautiful, surrounding countryside. During your time here, you should also visit the Jama Masjid Mosque, with its huge doors and go to the Caravanserai. These two sites have free entry, so be wary of kids trying to sell you tickets.
Most tourists go to Agra to see the Taj Mahal during their trip to India, so if you do so, I recommend you take time out to visit Fatehpur Sikri. Even if this site is overshadowed by the wondrous Taj Mahal, don't underestimate Fatehpur Sikri and it'll only take a day to tour.
When traveling India, it is cities like Fatehpur Sikri that leave a lasting impression. Once arrived in Agra, I traveled to Fatehpur Sikri, 30 minutes away by car. I went there a little by chance because I both didn't want to remain in Agra and was intrigued by this former Mughal capital.
I found myself absolutely enchanted by the charm of this city and the spectacular remains of its past. What an incredible mixture of different religious influences there is to be found in this immense, 16th century citadel!
I remember sleeping wonderfully well in a guesthouse facing the citadel's main ornamental pond and encountering very few tourists there, which was much to be appreciated after the crowds at the Taj Mahal!