On the way back to Spain from Portugal, we left the little town of Luz and took a short detour through the “big city” in this part of the Algarve region — Lagos, population 30,000.

What originally drew my attention was the town’s name — also the name of the biggest city (and former capital) or Nigeria. And, yes, the Nigerian megalopolis apparently was named after the small Portuguese town.

Turns out the European “Lagos” is one of those smallish places that do not look like all that much, in the 21st century, but which saw lots and lots of history pass through its gates, here in the southwest of Portugal.

Lagos was the home port for the early Voyages of Discovery, which led to Portugal projecting power and influence around Africa and to points further east, on the Indian Ocean.

That shipping traffic brought wealth to Lagos, way back in the 1400s, in the form of gold and trade goods.

It also brought sub-Saharhan African slaves, apparently the first to reach the European continent since Roman times, if not earlier, and Lagos opened Europe’s first slave markets, in 1444.

That is some weighty history, indeed.

Prince Henry the Navigator, the son of a Portuguese king, generally gets a lot of credit for backing improved sailing craft, the caravel, and encouraging Portuguese explorers to go ever further down the west coast of Africa, before rounding the Cape of Good Hope and exploring the east coast of the continent.

Prince Henry also took a 20 percent cut of all profits that flowed through Lagos, including on the sale of African slaves — who fetched high prices.

It would be easy to demand Prince Henry join the ranks of history’s scoundrels, but slavery was common around the Mediterranean Sea, especially in North Africa (known in the West as the Barbary Coast), and had been for centuries.

Pirates who raided the south coast of Portugal, in search of European slaves, were a particular problem, depopulating towns of the small kingdom.

If nothing else, the longstanding practice probably served as an example to the Portuguese of how their own sea raiders enslaving populations could be a profitable enterprise.

So, back to the original Lagos, here in Portugal. The current residents of the town do not seem agitated about their city’s slave-trading past. In fact, a museum stands where one of the slave markets operated. It is listed among the city’s attractions.

We drove through the town, of late known as a sunny resort for northern Europeans, and noted several modern signs of prosperity. A McDonald’s. New housing units on the edge of town. Luxury yachts in the port.

We were through the town in maybe 10 minutes. It looked tidy and interesting, but its status in 2017 does not begin to challenge its relevance in the days of Henry the Navigator and the dawn of European exploration and expansion — as well as the port of call for the continent’s first African slaves.

In Europe, sometimes, it is hard to guess at what sort of history a place had without doing some research. As in Lagos.