"But the real question is 60 years after independence (for most member states), why does ECOWAS think it's acceptable for a foreign power to build its headquarters?"

ECOWAS and the Chinese Ministry for Foreign Affairs did not yet respond to CNN's requests for comment.

Why did ECOWAS accept?

ECOWAS was established in 1975 to foster economic integration and collective self-sufficiency in West Africa.

"For me, reliance on GDP is the wrong way to determine how well a country's economy is doing," he says. Corruption in many West African governments, he explains, means "funds that are accrued for national growth are often not where they need to be," impairing a country's ability to contribute effectively to bodies such as ECOWAS.

Currently, ECOWAS' operations are spread across three buildings in the Nigerian capital, which both Taylor and Olayoku say are "outdated" and not fit for purpose. The China Development Bank Corporation will work with "an ECOWAS designated authority" to "verify records of account payments at regular intervals" throughout the construction process, according to ECOWAS.

'No such thing as a free gift'

It's not the first time China has constructed buildings at the heart of Sub-Saharan African politics for free.

In 2012, it handed over the ultra-modern African Union headquarters in Addis Ababa, Ethiopia. With a price-tag of $200 million, it was China's largest aid construction project since the 1970s. In 2017, China broke ground on a fully-funded $58 million parliament in Brazzaville, Republic of Congo.

"Obviously, the (ECOWAS) building itself doesn't mean that China is going to extend its influence, but it does send a signal that China is positioning itself as a trusted friend of African presidents," says Taylor. "That influences all sorts of decision making processes ... there's no such thing as a free gift."

While Beijing defends its aid practices on the grounds they are neutral and respect recipient nations' sovereignty, Chinese money is not wholly unpolitical.

China becoming an aid power?

As China grows as a world power, its aid programs in general are expanding globally, too. A study published last year by AidData, a research lab at the College of William & Mary, found the size of Chinese aid assistance to be much larger than previously believed.

"The Chinese government actually considers the details of its overseas development programs to be a state secret," AidData executive director Brad Parks told CNN.

The AidData study found that at least 70% of China's overseas aid was sent to Africa from 2000 to 2014. While the report noted that "Chinese aid substantially improves economic growth," it also deemed the majority of spending less than effective and warned it may undermine Western efforts to use aid to promote democracy and political reform, at a time when the US is pulling back on overseas spending.

Giving developing nations buildings designed to help their political institutions prosper is part of that expanded aid program, says Aaron Tesfaye, a professor in political science at William Paterson University, New Jersey.

"We are now seeing China being a responsible nation, with peacekeeping forces in Darfur and Mali," he says. "So I can see where financing ECOWAS is a step forward in that responsibility."

Taylor agrees that in some African nations, such as Ethiopia where China has built a metro in the capital city and connected the land-locked country to the ocean via the Addis-Ababa-Djibouti Railway, as well as built the AU headquarters, most people see Chinese construction projects as "positive."

"The cultural power of China in the world today is a reality and something that is being embraced, given its economy cannot be ignored," says Olayoku. "I don't see anything wrong with China building the ECOWAS headquarters, as long as it does not impose its values."

CNN's James Griffiths also contributed to this report.