Reasons why historic buildings took so long to construct -

Innovations in construction have significantly sped up development. It’s no surprise that many major projects, such as Dubai's towering skyscrapers and large dams worldwide, are finished in just a few years. Historically, it wasn't unusual for buildings to require decades or even hundreds of years to complete!

Click through the following gallery and build up a picture of some of the lengthiest construction projects in history, and find out what building took the longest to be signed off.

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St Paul’s Cathedral, England (40 years) -

Architect Sir Christopher Wren’s masterpiece, St Paul’s Cathedral in London, took nearly 40 years to build. Construction began in 1675 and was completed in 1711. However, the statues on the roof were added later, in the 1720s.

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Salt Lake Temple -

A temple of The Church of Jesus of Latter-day Saints, this huge structure in Salt Lake City, Utah required 40 years to complete. This was because much of the sandstone foundation had cracked while buried in an effort to disguise the construction site's location during the Utah War (1857–1858). The temple was finally dedicated in April 1893.

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Statue of Christ the Redeemer, Brazil (9 years) -

The Christ the Redeemer statue, arms outstretched crowning the peak of the 700-m (2,300-ft) Corcovado Mountain, overlooks Rio de Janeiro as a symbol of Christianity across the world. It took nine years to build, between 1922 and 1931. The concrete making up the base was supplied from Sweden. The statue's outer layers, however, are made from soapstone, chosen for its enduring qualities and ease of use.

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Saint Basil’s Cathedral, Russia (7 years) -

Built on the orders of Ivan the Terrible, Moscow’s colorful dome-topped cathedral took seven years to complete, between 1555 and 1561. The red brick used for construction was a relatively new material, and encloses an elaborate internal wooden frame running the entire height of the church.

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The Great Pyramid of Giza, Egypt (20 years) -

The oldest and the largest of the three pyramids in the Giza pyramid complex near Cairo, the Great Pyramid of Giza took an average workforce of 14,500 people 20 years to build. The pyramid consists of an estimated 2.3 million blocks, believed to have been transported from nearby quarries. It was completed in 2560 BCE.

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Cologne Cathedral, Germany (632 years) -

Germany’s most visited landmark is currently the tallest twin-spired church in the world. It took 632 years of construction to complete, starting in 1248 and finishing in 1880, though building work was halted in 1473 and not restarted until the 1840s.

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The White House, USA (13 years) -

The official residence and workplace of the president of the United States, the White House in Washington, D.C. was constructed over eight years, between 1792 and 1800. However, in 1814 the mansion was set ablaze by British forces in an attack that required a subsequent five years of reconstruction.

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The Coliseum, Rome (8 years) -

Begun on the orders of Roman Emperor Vespasian in 70 CE, construction of the coliseum took eight years to complete. Built by slave labor, the largest amphitheater ever created at the time took further teams of professional Roman builders, engineers, artists, painters, and decorators to undertake the more specialized tasks necessary for completing the structure.

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The Parthenon, Greece (9 years) -

Construction of the Parthenon in Athens began in 447 BCE, when the Athenian Empire was at its peak. It took the Greeks nine years to build, primarily by men who knew how to work marble. These quarrymen had exceptional skills and were able to cut the blocks of marble to very specific measurements—a highly specialized but laborious process.

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Hadrian’s Wall, England (10 years) -

Stretching 117 km (73 mi) from coast to coast across antiquity's Roman province of Britannia, Hadrian’s Wall was built to guard the wild and untamed northwest frontier of the Empire. Begun in 122 CE, it was largely complete within six years. However, the addition of milecastles (small forts) along the wall required another four years or so of labor.

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Angkor Wat, Cambodia (37 years) -

This Buddhist temple complex is the largest religious monument in the world. It was founded in the 12^th century, built over a period of 37 years between 1113 and 1150 from an estimated 10 million sandstone blocks hauled from Mount Kulen, a quarry approximately 40 km (25 mi) to the northeast.

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Milan Cathedral, Italy (579 years) -

The Duomo di Milano took nearly six centuries to complete, begun in 1386 on the orders of Archbishop Antonio da Saluzzo. The various phases of construction through wars and political upheaval meant it was only completed in 1965, when the last gate was inaugurated.

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Ulmer Münster, Germany (513 years) -

Ulm Minster in the city of Ulm is currently the tallest church in the world, with a steeple measuring 161.5 m (530 ft). Its foundations were laid in 1377, during the Gothic era. Major structural threats in the mid-15th century required reinforcing by a team of master builders. The Reformation and the Thirty Years' War also halted progress. The building was finally consecrated in 1890—513 years after its inception.

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Malbork Castle, Poland (126 years) -

The largest castle in the world measured by land area was created by way of gradual extension over 120 years. Construction, using only bricks, began in 1280 and was completed in 1406.

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Mount Rushmore, USA (14 years) -

It took 14 years to carve the heads of four US presidents—George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln— into the granite face of Mount Rushmore in South Dakota. Each president was originally to be depicted from head to waist, but lack of funding forced construction to end in October, 1941.

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Neuschwanstein Castle, Germany (17 years) -

Commissioned by Ludwig II of Bavaria, construction started on this fairytale castle in 1869 and was not completed until 1886, a period of 17 years, during which work took place day and night due to the monarch’s demanding and totally unrealistic deadlines.

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The Taj Mahal, India (21 Years) -

The world-famous ivory-white marble mausoleum in Agra was commissioned in 1632. It was constructed using materials from all over India and Asia, with over 1,000 elephants used to transport huge marble blocks. A workforce of 22,000 completed the building 21 years later, in 1653.

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St. Peter’s Basilica, Vatican City (144 years) -

Described as the greatest of all churches in Christendom, the present St. Peter’s Basilica was built between April 1506 and November 1626 —a period of 144 years. The church dome underwent several modifications during this time, with Michelangelo commissioned in 1547 to redesign what is still the tallest dome in the world.

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Sacsayhuamán, Peru (63 years) -

The historic 13^th-century capital of the Inca Empire, the massive walls and fortress of Sacsayhuamán, located on the outskirts of Cusco, Peru, took 63 years to build. It required hundreds of men to quarry and move the stones to the site, using ropes and brute force.

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Strasbourg Cathedral, France (424 years) -

It took over four centuries to complete Strasbourg's imposing cathedral, from 1015 to 1439. Its famous west front is decorated with thousands of figures, and is a masterpiece of the Gothic era. Likewise, the tower reflects a high degree of linearity captured in stone—examples of craftsmanship that took many decades to accomplish.

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La Sagrada Família, Spain (presently 142 years and counting) -

Construction on Antoni Gaudí’s extraordinary basilica in Barcelona began on March 19, 1882—and is still ongoing! This is due in part to lack of funding, but protests, politics, and civil wars have all played their part in the delay process. It's expected to be completed by 2026: 100 years after Gaudí's death.

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The Leaning Tower of Pisa, Italy (199 years) -

One of Italy's most beguiling landmarks, the tower's construction took 199 years to complete. Its foundations were laid in 1173. Building work was stopped twice, once after the structure began to sink into unstable subsoil, which caused it to lean, and again during the Battle of Meloria.

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York Minster, England (252 years) -

The city of York's splendid medieval cathedral took 252 years to build. Construction on the present cathedral began in 1220 and progressed well until the central tower collapsed in 1407. Work on a replacement, plus the addition of the two western towers, was finally completed in 1472.

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Buckingham Palace, England (262 years) -

The townhouse originally known as Buckingham House was completed in 1703. During the 19^th century, it was enlarged and became Buckingham Palace—and the London residence of the sitting British monarch. The Queen's Gallery was opened in 1965, 262 years after the inauguration of the original house.

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The Kremlin, Russia (364 years) -

The fortified complex in the center of Moscow known as the Kremlin is enclosed by walls built by Italian masters from 1485 to 1495. Several later churches, cathedrals, and palaces, including the landmark Grand Kremlin Palace, completed in 1849, constitute a building process that lasted 364 years.

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Chichan Itza, Mexico (400 years) -

Chichen Itza, a pre-Columbian era city built by the Maya people in Yucatán, includes El Castillo, also known as the Temple of Kukulcan. Following a timeline of other citadel buildings, it was erected over several stages of construction from around 600-1000 CE, about 400 years in total.

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Westminster Abbey, England (500 years) -

One of the United Kingdom’s most notable buildings, Westminster Abbey was built over a period of 500 years, starting in 1245. Many extensions followed, with the final commission, the two main towers, completed in 1745.

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Petra, Jordan (850 years) -

The Nabataeans carved and sculptured this extraordinary citadel into solid rock in 600 BCE, a process of construction that lasted nearly 850 years. Adept civil engineers, the Nabataean workforce put giant steps into the mountains so that the site could be surveyed properly before work commenced.

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Stonehenge, England (1,500 years) -

One of the most iconic and enigmatic structures found anywhere in the world, Stonehenge, a prehistoric monument located in Wiltshire, took Neolithic builders an estimated 1,500 years to erect. Archaeologists believe the enormous sarsen stones used in its construction came from a quarry 40 km (25 mi) north of Stonehenge on the Marlborough Downs.

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The Great Wall of China, China (2,000 years) -

Instantly recognizable, the Great Wall of China was built over several dynasties and epochs. At 21,196 km (13,171 mi) in length, the wall remains one of the most impressive architectural feats in history—and taking 2,000 years to complete, the longest construction project ever undertaken.

See also: Secrets behind famous monuments.

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