What will one day be the most populous city in Africa was initially ignored by the Portuguese explorers who first claimed it, served as a hub for a brutal slave trade and once held the hope of a continent that even now struggles to overcome its colonial past.

Lagos is an exciting, contradictory metropolis drawing millions through its streets daily hustling for success while darting between crumpled yellow minibuses, gang members and beggars. But the buildings that once dominated its skyline continue to disappear as a booming population, decay and neglect claim the city's rich architectural past.

Some preservationists have restored the ornamental archways of the city's Brazilian-style buildings and kept the wide-roofed British colonial homes of the past. However, they warn more needs to be done now before that history slips away forever.

By 2015, the population of the city of Lagos will reach 12.4 million people, making the city the most populous on the entire continent, according to a 2010 study by the United Nations' Human Settlements Program. By 2025, the U.N. estimates more than 15.8 million people will be crowded into the city on the mainland and its islands.

"The anticipated population boom is putting tremendous pressure on Lagos because she's surrounded by water," said Desmond Majekodunmi, the president of Legacy, a group trying to protect that architectural past.

Lagos Island was a swampy bog and forest until about 1660, when the Yoruba people of Nigeria's southwest established a permanent settlement there. That island became the base of what Lagos would become today: Nigeria's most populous city and soon to be Africa's as well.

Perhaps nowhere can that population crush be better seen than Lagos Island. Its marina side holds glass-tower headquarters for major banks, as well as the country's top office for Royal Dutch Shell PLC, the dominant oil firm in the crude-rich nation. On other parts of the island, a dozen family members can be found crowded into a single room, motorcycle taximen asleep on their bikes under overpasses and bars set up seats in the narrow streets at night.

The island's population saw its first boom amid the region's decimating slavery trade. That trade also saw the start of the eclectic architectural styles of the island, as the Portuguese built a palace of iron columns and tiles — a far cry from the palm-thatched roofs and mud walls of a typical home.

However, innovation remained severely limited in that time, as the traditional ruler there once arrested a man who used lime to whiten the walls of his home.

"Not only was his property seized, but he himself was cruelly put to death — a severe price to pay for progress," the history book "Building Lagos" by authors Kunle Akinsemoyin and Alan Vaughan-Richards wryly notes.

By the time the British took over Lagos amid its fight against slavery, the island's inhabitants had become more diverse. Freed slaves from Cuba and Brazil, as well as those from the newly founded nation of Liberia, arrived in Lagos. They brought with them the memory of homes in their former Latin American countries: decorative moldings around windows, two-story homes of brick with wide windows and gardens.

The British brought the large colonial homes with tin roofs still standing today in some areas of Lagos today. The U-shaped secretariat with its two towers once stood out as the dominant building along the island's waterfront, greeting those coming in from the ocean.

Today, the musty building holds moldering books and darkened offices where Nigeria's colonial rulers once worked. Nearby, the island's iconic 25-story Independence House, a gift from the British to Nigeria ahead of its independence in 1960, sits empty as well. The black-glassed Savannah Bank building, which was to be the home of the financial firm before it failed in 2002, has no tenants. And the island's tallest building, the 32-story NITEL building, is named after the country's collapsed state-run telephone company.

Politics and governance plays a large part in the architectural slump. Nigeria moved its federal capital from Lagos to Abuja, a newly built city near the country's center, in the 1990s. There, new freeways and massive government buildings rise out of the red-dirt clay of the city, an almost sterile city-in-a-box for a nation used to erratic building and little regulation.

There are some efforts now at preserving that heritage, with a few buildings on Lagos Island recently restored, as well as an 1898 building at the nearby Nigerian Railway Corp. compound. While the old Broad Street Prison was torn down, Lagos state recently opened Freedom Park there, with neatly manicured grass, performance space and exhibits noting the site's history.

For John Godwin, an architect who arrived in Nigeria in 1954 from Britain and later became a citizen, Lagos Island is both his home and a bittersweet sight. Godwin spent his career designing some of the country's most iconic buildings with his wife, later serving as a professor at the University of Lagos. He restored the old railway compound house and works on preservation issues with Legacy.

"You have to say that in many areas of Lagos, those building bylaws have been totally ignored," Godwin told The Associated Press in a recent interview. "I think it is making it very difficult for people to live here, I really do. And I think as much as they know that, Lagos is like a drug."

Godwin paused at one moment to collect himself while thinking about his 58 years in the country.

"You get emotional about it," he said, tearing up. "It's a mess. But under that mess, there are a whole lot of very good people."


Jon Gambrell can be reached at www.twitter.com/jongambrellap.