For the Geo Quiz, we're looking for a major hub of Nigeria.
This city is the capital of the north-central state that bears the same name.
The city was founded by the British in the early 20th century.
Both Muslims and Christians coexist there.
Though there have been serious religious tensions, especially after the implementation of Sharia law in 2001.
There are some serious environmental issues there as well.
Because drinking tap water is not safe in Nigeria, people consume a lot of bottled water and that creates *a lot* of trash.
One non-governmental organization thought it'd be a good idea to use those empty plastic bottles as building materials.
In fact, they're building homes a few miles outside the Nigerian city we're looking for.
What's its name?
The answer is Kaduna, in northern Nigeria.
And just outside of Kaduna, you'll find the village of Yelwa.
That village is now the site of Nigeria's first-ever house built from recycled plastic bottles.
It's a one bedroom set-up with all the comforts of home.
It required 8,000 bottles, and built in the round style of traditional Northern Nigerian houses.
The BBC's Sam Olukoya saw it for himself.