World’s fairs have launched some of our boldest and most iconic structures, from Paris’ Eiffel Tower to Seattle’s Space Needle, but there were plenty more wild ones left on the cutting-room floor. These fantastical structures — think a 1,000-foot guillotine or a 1,000-mile slide — represent an era of architectural ambition and wonder.

2. The Basilica of Our Lady of Peace, Ivory Coast

The world’s tallest basilica was commissioned by Félix Houphouët-Boigny, the “founding father” of Côte d'Ivoire, and is situated in Yamoussoukro, the country’s political capital. The exact cost of its construction is shrouded in controversy, but it was built from 1985 to 1989 with marble from Italy and stained glass from France. At full capacity, 18,000 worshippers can fit into the basilica — a space the size of 13 football fields — but typically only a few hundred people attend Sunday services. Widely believed to have been funded by Houphouët-Boigny dipping into the treasury, it is sometimes derisively referred to as “basilica in the bush” or “Our Lady of Treasury.”

The 2,000-year-old Temple of Baal, an architectural wonder constructed by Greco-Roman architects with Persian influences for the Mesopotamian deity Baal, has been one of several UNESCO World Heritage sites that have been decimated by ISIS in recent years. Only its exterior remains standing today. But one artist is preserving Palmyra … in metal. Ohio artist Leila Khoury has been re-creating her parents’ home from the memory of her childhood visits.

4. Angkor Wat, Cambodia

Temples sprawl across the complex in varying shapes, sizes and states of decay, with some buildings taking on a mystical appearance as they're swallowed up by trees and roots. Huge stone faces jut out in all directions and intricate bas-reliefs line the walls and doorways. And the architectural jewel owes its existence to an engineering catastrophe. A water reservoir critical for large-scale agriculture in the Koh Ker area collapsed around the time the Khmer capital moved back to Angkor in the 10th century. That’s where Khmer King Suryavarman II ended up building his state temple and eventual mausoleum.

Many of the issues American society grapples with today stem from decisions made almost 250 years ago. OZY readers now have the chance to join Allen C. Guelzo for a deep dive into how each of America's Founding Fathers played a unique role in shaping the grand story of the U.S. Constitution. Sign up for The Great Courses Plus today for a free month of exclusive access.

1. Modular Construction

The COVID-19 pandemic has highlighted the need to design and build quickly in emergency situations: Think hospitals, quarantine centers, testing sites and temporary lodging. Given this demand and urgent need for these spaces, custom-made modular construction — the result of innovative product technology paired with good design — has become the key to meeting diverse needs.

Over the past decade, crowded urban settings from New York to Chicago to San Francisco have embraced micro apartments — with an area less than 400 square feet — as an important housing option. But now these small living spaces the size of a school bus are cropping up in huge numbers in sprawling suburbia as lifesavers for communities starting to see an influx of millennials. Expect to see more of them with the pandemic spurring a reverse migration from urban cores, and economic wreckage putting a premium on budget living.

3. Flexible Homes

As the world continues to adapt to COVID-19 and lifestyles of most individuals change drastically, Australian architectural practice Woods Bagot has a solution for flexible living — in your home. While most houses aren’t ideal spaces for work-from-home desks, quarantine living, home gyms, etc., AD-APT aims to change that. The system involves a series of adjustable walls and screens that segment an open-plan apartment into various dedicated spaces.

4. Afrofuturism

New models to solve the issue of congestion in sprawling megacities across Africa are on the rise. They represent an architecture that draws from African tradition, such as vibrant street markets, and adds a layer of modernism, sometimes even with a sci-fi flair.

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If the cement industry were a country, it would be the third-largest emitter of carbon dioxide in the world — it released 2.8 billion tons of CO2 in 2016, according to the Chatham House think tank. That’s something a new breed of architects in India want no part in. And that’s why they have gone back to building mud houses. Houses built with sun-dried bricks made of mud and cow dung can cost the same as a regular building, but they use far less water and other resources.

2. Destination Airports

Singapore’s jewel is an airport terminal with the world’s tallest indoor forest, a waterfall and an assortment of luxury retail outlets and restaurants. Designed by Israeli-Canadian architect Moshe Safdie, the 10-story, $1.25 billion building has an aluminium-and-steel framework designed to illuminate the complex with natural light. Singaporean authorities say they want the new terminal, which opened last year, to be a tourist destination too — the first such attraction globally.

3. Mind Over Matter

Growing up in central Burkina Faso, Diébédo Francis Kéré, a Berlin-based architect, had to travel more than 25 miles to a poorly lit school with inadequate ventilation. To help other village children, he designed an ecological structure back in 2001. It was a custom school with perforated ceilings and walls made of locally sourced materials like mud and clay, as well as a simplified process that allowed the villagers to participate in the construction. The project has grown into a large educational complex, and Kéré is now at the forefront of a new generation of African architects who are breaking down barriers.

Imagine standing inside a gigantic wine barrel. Nearly 50 feet in diameter, the barrel could hold almost 550,000 gallons of wine — if it were ever to be filled with wine. Instead, Durkheimer Fass, the barrel, is a restaurant and a landmark on the German Wine Road, or Weinstrasse, and home to some amazing sauerkraut.

2. Basket Building, Ohio

This humongous basket, with its giant handles, is quite a spectacle from a bird’s-eye view. It was designed to mirror the presumed quality of the handcrafted maple wood baskets made by Longaberger Basket Co., which housed its headquarters there until the firm folded. The seven-story building is now on its way to becoming a luxury hotel.

3. Turning Torso, Sweden

The Turning Torso is a neo-futuristic residential building in Malmö — and the tallest in all of Scandinavia. This skyscraper twists a full 90 degrees from bottom to top. How did it come about? Turning Torso was actually inspired by a sculpture called Twisting Torso, made entirely from white marble by engineer, architect and sculptor Santiago Calatrava. The building, also designed by Calatrava, consists of nine five-story pentagon segments stacked one on top of the other.

4. Dubai Frame, UAE

If Quidditch were not a fictional sport, this frame-shaped building would be the perfect spot to test flying brooms. Still, the landmark monument is just as magical and, with dimensions of nearly 500 by 350 feet, the world’s largest frame. Furthermore, its ownership is embroiled in controversy: The designer whose entry was the winner in a competition organized by the Dubai emirate claims to have been denied credit in the execution of his idea.

1. Shigeru Ban

How many architects literally use paper to actualize dreams they laid out on paper? Ban, 63, leaped ahead of his peers years ago by using recycled cardboard tubes in designing low-cost shelters for people displaced by natural disasters or violence. He’s helped Rwandan genocide refugees, and Japanese and Haitian earthquake survivors. He’s also adept at finessing commercial projects like La Seine Musicale, the French cultural center with an egg-shaped auditorium and a public garden rooftop.

While most of her professional peers are consumed by working in steel and concrete, Terki is trying to reacquaint Algerians with a humbler material, one their ancestors started using 15 centuries ago: plain old earth. Through her work with the Ministry of Culture, she is racing to preserve the country’s singular earthen architectural heritage (there are 10,000 homes just in Timimoun, where she is based), including the beautiful “Berber castles” and forts called ksars.

As CEO of the Strelka Institute for Media, Architecture and Design, a pioneering urban studies think tank, Melnikova has overseen a concerted effort to promote the discipline in Russia while also attempting to fashion Moscow into a global destination for city planning.

Palazuelo, a Spanish restorer of historical sites, is molding cities’ pasts into their future. Witness his work in Lima, Peru, where he bought dozens of historic buildings in the city center and restored them beautifully. Now he’s setting his sights on Detroit. “Cities are living beings that move and change every day,” he says. “They are like women: There are no two alike.”