Emperor Hadrian's rebuilt Pantheon in Rome, crowned by the largest unreinforced concrete dome ever built, neared completion around this period, a feat unmatched for over a millennium.

Emperor Constantius II dedicated the first church of Hagia Sophia in Constantinople, beginning a site that would host three successive great churches.

Byzantine Emperor Justinian I dedicated the Hagia Sophia in Constantinople, then the largest cathedral in the world.

Byzantine Emperor Phocas gave the ancient Roman Pantheon to Pope Boniface IV, who consecrated it as a Christian church, ensuring its survival for over a thousand years.

Burmese tradition marks the founding era of Bagan, whose plains would eventually hold over 2,000 Buddhist temples and pagodas.

Florence installed Michelangelo's 17-foot marble David outside the Palazzo della Signoria as a civic symbol of defiance.

Tokugawa Ieyasu ordered construction of Nagoya Castle to begin, a massive fortress meant to secure Japan's strategic Tokaido road and project Tokugawa dominance.

Revolutionary France formally opened the Louvre palace to the public as a museum, transforming a royal residence into a symbol of shared national heritage.

Workers break ground near Rome, New York, beginning construction of the Erie Canal, a 363-mile waterway linking the Great Lakes to the Atlantic.

British and French troops began the systematic looting and burning of Beijing's Old Summer Palace, destroying centuries of Chinese imperial art and architecture during the Second Opium War.

After ten years of digging by tens of thousands of laborers, the Suez Canal opened, linking the Mediterranean and Red Seas and reshaping global trade.

The 120-mile Suez Canal, linking the Mediterranean and Red Seas, formally opened for shipping traffic, cutting the sea route between Europe and Asia by thousands of miles.

The Eads Bridge across the Mississippi River at St. Louis opened, the first major bridge built with steel and the first to use pneumatic caissons in America.

Construction began on the crypt of Barcelona's Sagrada Família, the basilica that would consume architect Antoni Gaudí's life and remain unfinished more than a century later.

Engineers Maurice Koechlin and Émile Nouguier draft early sketches for a colossal iron tower, a concept that would become the Eiffel Tower.

The last crate of the dismantled Statue of Liberty arrives in New York Harbor aboard the French ship Isère, ready for assembly.

President Grover Cleveland dedicated the Statue of Liberty in New York Harbor before a flotilla of ships and cheering crowds.

Gustave Eiffel received the Grand Cross of the Legion of Honour, capping the year his iron tower reshaped the Paris skyline and global engineering ambition.

American inventor and journalist Sara Duncan makes headlines as one of the earliest documented ascents of Paris's newly finished Eiffel Tower by an American woman.

American engineers formally began construction of the Panama Canal, resuming a project that had already claimed thousands of lives under French management.

New York's first underground rapid transit line opened, carrying 150,000 passengers on its first day and transforming the growing metropolis.

The SS Ancon became the first ship to officially transit the newly completed Panama Canal, linking the Atlantic and Pacific Oceans through 51 miles of locks and channels.

The SS Ancon became the first ship to make a full official transit through the newly completed Panama Canal, linking the Atlantic and Pacific oceans.

The SS Ancon made the first official transit through the newly completed Panama Canal, linking the Atlantic and Pacific oceans after a decade of construction.

The SS Ancon becomes the first ship to officially transit the newly completed Panama Canal, linking the Atlantic and Pacific oceans.

The cargo ship SS Ancon made the first official transit of the Panama Canal, completing a 51-mile passage that reshaped global trade and naval power.

The first hydroelectric generator at Hoover Dam began transmitting power to Los Angeles, 266 miles away, marking the completion of the world's largest dam.

The first generator at Hoover Dam began transmitting electricity to Los Angeles, 266 miles away, proving the massive Depression-era project's ambition.

Ground was broken on the Pentagon, a five-sided military headquarters built at breakneck speed in just 16 months on the eve of America's entry into World War II.

After fourteen years of blasting granite in the Black Hills, sculptor Gutzon Borglum's monument to four presidents is declared finished.

Allied firebombing raids destroyed much of Nagoya, Japan, including the centuries-old Nagoya Castle and its famous golden shachihoko ornaments.

Not the famous 1940 collapse, but a related Pacific Northwest bridge disaster raised fresh fears about wind-sensitive suspension designs.

Frank Lloyd Wright's spiraling Solomon R. Guggenheim Museum opened to the public in New York City, six months after the architect's death.

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Workers finished hoisting the final antenna section atop Toronto's CN Tower by helicopter, completing the structure that would be the world's tallest for 32 years.

Construction officially begins in Dubai on what will become the Burj Khalifa, the tallest man-made structure ever built.