Stone Spheres of Costa Rica: The Diquís Mystery

In southern Costa Rica, some of the most remarkable archaeological objects are also among the hardest to explain. Large stone spheres lie scattered across the landscape, their surfaces shaped by people who lived centuries before the arrival of Europeans. Some were moved from their original positions, while others survived in the places where archaeologists can still study them.

Pre-Columbian stone spheres from Costa Rica’s Diquís region displayed at the National Museum in San José. These remarkable stone objects are an important symbol of the country’s cultural heritage.

Seattle Underground: The Buried Streets Beneath Pioneer Square

Most visitors to Seattle head straight for the Space Needle and Pike Place Market. Many people do not realise that a few feet below Pioneer Square, the shopfronts and sidewalks of an older Seattle still sit in the dark. The Seattle Underground tour is the simplest way to see them, and it is one of the stranger, funnier history lessons in the Pacific Northwest. Here is how the buried city came about, which tour suits you, and what to know before you book.

Seattle Underground: Historic Passageways Beneath Pioneer Square

Pisonia Tree: The Birdcatcher Tree and Its Sticky Seeds

A seabird brushes past a branch and flies off with a few seeds stuck to its feathers. For most plants, that’s a positive outcome. For the Pisonia tree, it can turn into a disaster for the bird.

Sticky fruits from the Pisonia tree cling to a noddy seabird’s feathers, illustrating how the tree disperses its seeds and how excessive entanglement can interfere with a bird’s flight.

Hanging Lake: Colorado’s Turquoise Lake in Glenwood Canyon

Hanging Lake is one of the most unusual sights in Glenwood Canyon, Colorado. The small lake is known for its clear turquoise water, pale mineral formations, and waterfalls that flow over moss-covered rocks. Set on a steep mountainside near Glenwood Springs, it looks quite different from an ordinary mountain lake.

Hanging Lake sits high above Glenwood Canyon in Colorado and is known for its clear water, mineral formations, and surrounding waterfalls.

Montmartre Cemetery: Paris’s Historic Cemetery Beneath a Bridge

In Paris, a busy metal bridge passes above a cemetery filled with old tombs, leafy paths and monuments to some of France’s best-known artists and writers. This unusual place is Montmartre Cemetery, also called Cimetière de Montmartre or the Cemetery of the North. Opened in 1825, it occupies the site of former gypsum quarries in the city’s 18th arrondissement.

The Caulaincourt Bridge passes directly over Montmartre Cemetery, creating an unusual contrast between the busy city streets and the historic burial ground below.

Le Mur des Je t’aime: Paris’s Wall of Love

In a small garden square in Montmartre, Paris, a wall carries a message that needs no grand speech or elaborate explanation. The words Je t’aime—French for “I love you”—appear across a blue tiled surface in hundreds of written forms. Known as Le Mur des Je t’aime, or the Wall of Love in Paris, this unusual artwork brings languages and cultures together through one of the simplest expressions of human affection.

Le Mur des Je t’aime brings declarations of love together on a blue-tiled wall in Montmartre.

IJsseloog: The Artificial Island That Stores Contaminated Silt

A circular island in the middle of a Dutch lake might look like an unusual piece of land reclamation. But IJsseloog has a far more specific purpose: it was built to contain contaminated sediment removed from the lakebed. The project brings together water management, environmental engineering and an attempt to deal with pollution left behind by decades of industrial activity.

IJsseloog is an artificial island in the Ketelmeer, Netherlands, designed to contain contaminated dredged sediment. 

16th Avenue Tiled Steps: San Francisco’s Mosaic Staircase

In a quiet residential neighbourhood of San Francisco, California, an ordinary flight of outdoor steps has become an extraordinary work of public art. Known as the 16th Avenue Tiled Steps, this colourful staircase carries visitors through a mosaic world of sea creatures, animals, birds and celestial designs. From a distance, it looks like a giant painting spread across a hillside. When viewed up close, thousands of individual pieces come together to tell a much bigger story.

The 16th Avenue Tiled Steps, also known as the Moraga Steps, feature a colourful sea-to-sky mosaic created by artists and local residents in San Francisco.

Wenceslas on an Upside-Down Horse: Prague’s Bizarre Statue

Inside a passage in central Prague, a familiar figure from Czech history appears in a rather unfamiliar position. Saint Wenceslas, the traditional patron saint of Bohemia, sits calmly on the belly of a dead horse suspended upside down from the ceiling. The horse hangs by its legs, its head pointing towards the floor.

David Černý’s unusual sculpture depicts Saint Wenceslas sitting on the belly of an inverted, lifeless horse. Created in 1999, the artwork hangs inside Lucerna Palace in Prague, Czech Republic.

Taum Sauk Hydroelectric Power Station: The Mountain-Top Power Plant

The Taum Sauk Hydroelectric Power Station in Missouri has an unusual way of storing energy. Instead of keeping fuel on site, it uses two reservoirs at different elevations. When electricity demand is low, pumps move water uphill to a reservoir on Proffit Mountain. Later, the water flows back down through turbines to generate electricity.

The Taum Sauk Hydroelectric Power Station in Missouri uses pumped-storage technology to store energy by moving water to an elevated reservoir for later electricity generation.