
The old walled city of Harar used to be strictly off limits for non muslims. It was one of the most holy cities of the country.
In the west it is also famous for the fact that the French Poet Arthur Rimbaud lived here for a while. His house is still one of the most important sights of the city. Other sights include the friday mosque and the old city walls.
Harar is on the train line from Addis ababa to Djibouti. This line was built by the French and there is still a French language girls school in the town. So if you happen to speak French you may be able to get around with it more easily than with arabic.