First you have to know that Nigeria is a very populated country, being Africans most populated with a very vast land. In Nigeria we have three major regions; the south south, North, and South West.
Oh! And the middle belt, making it four major regions.
South South- most developed region but as a foreigner, you are likely to get kidnapped there but it happens rarely. The biggest city in the south south is Portharcourt city. Followed by akwa ibom, calabar, and asaba
North - the north is the undeveloped region and you're most likely to get bombed there but it depends on which state you are. Kaduna and kanu is safe and quite developed but there is a record of terrorism in other states especially Born state.
South west- this region follows the south south in development but we have the most busiest and developed city in the south south which is Lagos city. Think of Lagos as Mumbai, very busy, tall buildings, traffics and all� Lagos has lots of foreigners there and it's quite safe.
Middle belt- this is where we have another big city named Abuja, which is also the capital of the federal republic of Nigeria.