Mazar-i-Sharif is located in northern Afghanistan, close to the old city of Balkh. The name of the city means something like Tomb of The Chosen One.
The main sight in town is the great Blue Mosque, Tomb Of Hazrat Ali, cousin and son-in-law of Prophet Mohammad. The tomb was covered with earth to escape the ravage of Genghis Khan in 1220 and remained lost until it was uncovered during the rebuilding work in 1480s.
Please note that according to many (western) governments it is not safe to travel to Afghanistan. Although the country is very beautiful and travel will be very exciting it will also be quite dangerous.