Arusha has about 350 000 inhabitants in the North of Tanzania
Thanks to the Kilimanjaro Internatioal Airport (50 km) Arusha is a popular the starting point for many of the tourists who want to do safaris to Serengeti or Ngongoro crater, Arusha is often the first place where tourists arrive.
Many middle or upper class hotels provide a good infrastructure for tourists. And if you didn't book your safari at home yet in Arusha you will find lots of tour operaters providing all kinds of trips and safaris.
Karibu Hostel in Arusha is a cheap alternative for low budget travellers as well.
Arusha itself has also a national park only 15km outside of the city where you can whatch giraffes, buffolos and lots of other wild animals