104 Kilo Meter from Addis and after two hours drive in the North, you will reach to Debre Libanos Monastery and the Blue Nile gorge. The Monastery was founded by the famous Ethiopian Saint Tekle Haimanot in the 13th Century. And about 500 monks are living now. The Church has a beautiful stain glasses depicting stories from the New Testment and Old Testment. There is also a museum next door having different artifacts from the precious kings and Ethiopian Orthodox Pops.
After visiting the Monastery, drive up the four Kilometer up and park your car at Ethio - German Hotel. After having some refreshment, hike/trek to the Portuguese bridge and the Blue Nile gorge. It takes about 20 minutes walk to reach to the bridge. The best time to visit it is July- October. There is a beautiful waterfall at that time.
Around the gorge you also able to see the endemic Gelada Baboon.