The city of Aksuma, home of many obelisks, castle ruins, and tombs.
Some tombs in the city of Aksum have people that have been dead since 1st Century CE. It's a really old city.
There is also the town of Lalibela. A very historic town that represents one of the first times that Ethiopia converted from Judaism to Christianity. It's really important as it has 3 stone-carved churches.
The Sof Omar cave is the largest cave in all of Ethiopia, measuring at about 15.1 kilometers (9.34 miles) it's claimed to be one of the largest caves in all of Africa.