DARK SECRETS: What building took the longest to build | Rare Historical Photos

Construction Timeline: 1386- 1965 (579 years)
 
Milan Cathedral was a project so vast and ornate that generations of architects continuously revised the design.

Funding problems, changing artistic tastes, and endless decorative additions kept construction moving at a glacial pace.

Unlike many medieval cathedrals, the delays were not caused entirely by war or abandonment; builders simply kept adding more details, more statues, and more elaborate marble work.
 
This stunning cathedral contains thousands of statues and is home to one of the world's largest collections of Gothic sculpture.

Napoleon found it so beautiful that he even ordered that construction be sped up in 1805 so he could host his coronation as King of Italy there. Officially, it was completed in 1965 and still stands proudly today.

Construction Timeline: 1220- 1472 (252 years)
 
York Minster is one of the best-known Gothic cathedrals in the UK, but its design actually worked against its construction. As Gothic architecture evolved, so too did the plans.

Builders also faced fires, political unrest, and the sheer complexity of constructing enormous stained-glass windows and vaulted ceilings. It endured over 250 years of construction to reach its final form.

Its monumental Great East Window is among the largest medieval stained-glass installations in the world. Entire generations of craftsmen spent their lives working on only small sections of the church.

York Minster is currently one of England’s largest religious buildings, with private donations ensuring its continuous upkeep.

Construction Timeline: 1882- 2026 (144 years)
 
Antoni Gaudí's masterpiece (which he never saw in its final form) has become the ultimate symbol of endless construction.

Originally designed as a relatively ordinary church, the project became an enormous architectural experiment when Gaudí took over in 1883.

Progress slowed dramatically after Antoni Gaudí died in 1926, and the Spanish Civil War later destroyed many of his original plans and models, forcing architects to reconstruct plans from fragments.
 
But the finished product is a triumph of Gothic architecture, with towering spires, interior columns designed to mimic trees, and stained-glass windows that reflect the colors of sunrise.

It was finally finished earlier this year, the centenary of Gaudí’s death, although further decorative work may take place.

Construction Timeline: 1344- 1929 (585 years)
 
If there's any building that has faced almost every roadblock imaginable, it's St. Vitus Cathedral, which took almost six centuries to complete.

Wars, plagues, fires, and political uncertainty all interrupted work on Czechia's most important cathedral. Construction slowed dramatically after the Hussite Wars and remained incomplete for centuries.
 
St. Vitus is a stunning mix of Art Nouveau and medieval Gothic architecture, with a crown-jewel treasury and stained glass windows designed by Czech painter Alphonse Mucha.

Nowadays, visitors can marvel at over 500 years of design choices and cosmetic rehabilitation.

Construction Timeline: 1113 A.D- 1150 A.D (approx 37 years)
 
Angkor Wat took practically no time at all to build compared to others on this list, but that doesn't mean it wasn't stubborn!

Major construction occurred relatively quickly compared to that of European cathedrals, but it then became part of a larger, centuries-long program of temple expansion throughout the Khmer Empire.

Labor demands, complex water systems, and shifting royal priorities stretched developments across centuries.
 
It's currently the largest religious monument in the world, with over 2,000 carvings and a complex so vast it covers over 400 acres.

Its finished form has not been touched for a long time, preserving that authentic Cambodian craftsmanship.

Construction Timeline: 1248- 1880 (632 years)

Cologne Cathedral began as an ambitious Gothic-style monument designed to house ancient relics believed to have belonged to the Three Wise Men.

Medieval builders completed parts of the church before money troubles and political instability set in during the 1500s. For centuries, the unfinished cathedral stood frozen in time, and construction only resumed in the 19th Century.
 
When completed in 1880, Cologne Cathedral briefly became the tallest building in the world. Builders at the time used surviving medieval blueprints to complete the structure almost exactly as originally planned.

Today, it's a UNESCO World Heritage Site and one of Germany's most-visited landmarks.

Construction Timeline: 3rd Century BC- 17th Century AD (over 2,000 years)
 
The Great Wall of China is one of the longest construction projects ever, both in terms of time and length.

Chinese dynasties spent centuries building, rebuilding, and expanding defensive walls to protect their territories from invasions and raids.

Construction continued during the Ming Dynasty after repeated military threats exposed weaknesses in earlier defenses. However, the sheer size and scale of the wall slowed progress, as did harsh weather and difficult transportation.
 
According to EBSCO, up to 800,000 workers have participated in its construction over centuries, including laborers, soldiers, and prisoners.

Contrary to popular myth, it is not visible to the naked eye from space, but its enormous length still makes it one of humanity’s most extraordinary engineering achievements.

Today, the longest structure ever built attracts millions of visitors each year.

Construction Timeline: 1869- 1892 (23 years)
 
Most people would love to design their fantasy castle, but King Ludwig II of Bavaria actually did. Neuschwanstein Castle is the result of 23 years of fussiness, which caused endless delays and rising costs.

According to Schloss Neuschwanstein's official records, this castle was based on the Middle Ages and on the new Versailles. Ludwig died in 1886, but construction officially continued until 1892.

This beautiful castle actually inspired the one in Disney's Sleeping Beauty. Despite its medieval appearance, it used advanced 19th-century technologies, including central heating and running water.

Some consider the castle technically unfinished, but no further work is currently being done on it.

Construction Timeline: 8th Century- 9th Century (approx 100 years)
 
Borobudur's original construction is a bit of a mystery. It likely required decades of labor to build, with millions of volcanic stone blocks, and later volcanic eruptions and jungle overgrowth buried the structure for centuries. Its stubbornness lies more in the fact that it refused to crumble away, despite the trials of time.
 
This monument contains more than 2,600 relief panels and hundreds of unique Buddha statues arranged into a giant spiritual mandala.

While the original structure is strong, major restoration projects throughout the 20th century helped save the monument from collapse, preserving it for centuries to come.

Construction Timeline: 2589 BC – 2504 BC (approx. 85 years) 

They’re one of the most iconic sites in the world, but they haven't always been around. The Pyramids of Giza were built over roughly 85 years during Egypt's Fourth Dynasty, with each ruler commissioning increasingly ambitious tombs to demonstrate divine power.

Builders had to move millions of limestone and granite bricks, many weighing several tons each, without modern machinery.
 
The Great Pyramid of Khufu remained the tallest man-made structure on Earth for nearly 4,000 years. The pyramids are aligned with remarkable accuracy to the cardinal directions, showcasing the advanced mathematical and astronomical knowledge of ancient Egyptian engineers.

There are plenty of hidden chambers and passageways explored by archaeologists and tourists each year.

Construction Timeline: 3100 B.C- 1600 B.C (1,500 years)

Stonehenge evolved gradually over centuries, rather than being built all at once. Early builders created a circular earthwork enclosure, which later generations added to with massive standing stones, burial sites, and carefully aligned architectural features.

According to the BBC, the famous bluestones were moved from Wales to southern England by humans, though there's long been a belief that glaciers naturally transported them.
 
The monument has likely shifted over time, but remained untouched by human intervention. Stonehenge is famously aligned with the summer solstice sunrise, suggesting advanced astronomical understanding among its creators.

Naturally, it's now a UNESCO World Heritage Site and one of the UK's most visited monuments.

Construction Timeline: 1984- present (42 years)
 
The Palace of Parliament was designed to be a formidable building, described by Romanian dictator Nicolae Ceaușescu as a “victory of socialism.”

The project consumed enormous national resources before the regime collapsed in 1989, but even before that, progress was halted by its unprecedented size, budget crises, and its deliberately staggered plans.
 
It’s the heaviest of all historic structures, with thousands of rooms, a network of underground tunnels, and a nuclear bunker.

Perhaps due to its sheer size, some of the palace remains incomplete and underused today, and is considered "permanently unfinished" to this day.”

Construction Timeline: 1881- 1914 (33 years)
 
From the moment work began, the Panama Canal project faced every setback imaginable. The first major construction attempt began under French rule in the 1800s, but Panama’s mountainous terrain, relentless rain, and mudslides quickly overwhelmed the effort.

Thousands of workers also died from malaria and yellow fever, causing the project to be abandoned until 1904, when the US took over its project management.

They redesigned plans, reduced disease outbreaks, and introduced game-changing lock systems.

Today, the canal transformed global trade by allowing ships to avoid the long journey around South America’s Cape Horn.

Entire towns, railways, and artificial lakes were created to support construction and operation. Major expansion in the 21st century further increased its efficiency.

Construction Timeline: 1987- present (39 years)
 
Few modern projects symbolize stubborn ambition quite like the Ryugyong Hotel. Initially designed as a futuristic luxury skyscraper, construction stalled in the 1990s during North Korea’s economic collapse.

For years, the unfinished concrete pyramid dominated Pyongyang’s skyline as one of the world’s tallest unoccupied buildings.
 
At 1,083 feet (330 meters) tall, it dominates the landscape, with a heavy reinforced-concrete body, reflective glass paneling, and 14 floors.

Reportedly, large parts of the interior are still unfinished, casting doubt on this mega-project’s prospects for modern construction.

Construction Timeline: 1892- present (134 years)
 
This enormous Episcopal cathedral faced a series of challenges since construction began in 1892. From constant redesigns to financial setbacks to changing architectural visions, this was one stubborn basilica.

A devastating fire in 2001, which shattered windows and scorched artwork, necessitated additional repairs and further delayed progress.
 
The Basilica of St. John the Divine combines Romanesque and Gothic styles, creating a uniquely beautiful mix of designs.

This is because architects changed plans after construction had already started. It may still be unfinished, but it's been partially functional for decades and continues to attract visitors.