I have had this question for a LONG time. I acquired Spanish citizenship 6 years ago; I'm originally from Nigeria. Every time I want to travel to Nigeria the same question comes up: Can I travel to Nigeria on my valid Spanish passport together with my EXPIRED Nigerian passport and go visa-free? This will be the 4th time I'll be paying for a visa I'm never really sure I need?
Any backed up information would be REALLY appreciated!!!!