Discovering the Biggest Arch in the World: An Engineering Marvel

From the grandeur of ancient aqueducts to modern bridges and monuments that seem to defy the laws of physics, engineered arches have long stood as symbols of human ingenuity and architectural prowess. Unlike natural arches which, thanks to the relentless forces of weather and erosion and the passing of thousands of years are just, sort of, there, engineered arches are meticulously designed structures that distribute weight and withstand immense pressures, allowing for the construction of buildings, bridges, and monuments that shape the skyline.

But where is the largest arch in the world and what was – or is – the biggest ever arch? Read on to find out.

The history of engineered arches dates back to the great civilisations of the ancient past. The Mesopotamians in the second millennium BC used simple arches in construction, as did the Egyptians, but it was the Romans who truly harnessed their remarkable potential. From the pragmatic network of aqueducts that supplied water to their cities, to the wonderfully and excessively monumental arches like those adorning the Colosseum, these ancient arches were both practical and beautiful.

Over the centuries, arch architecture evolved significantly. The Middle Ages introduced the pointed Gothic arch, allowing for taller and more slender structures like the staggering masterpieces of the Cathedral of Notre-Dame in Paris, Westminster Abbey in London, and Cologne Cathedral in Germany. The Industrial Revolution brought new materials such as iron and steel to the fore, revolutionising arch construction and leading to today’s modern marvels.

So where is the biggest arch in the world, and is it the same as the biggest ever arch?

There are several types of engineered arches, each with unique characteristics suited to different architectural and engineering needs. The Roman (semicircular) arch, Gothic (pointed) arch, elliptical arch, and parabolic arch are among the most common. Modern engineering has also introduced the tied arch and the network arch, which incorporate tension elements to support greater loads and longer spans. These variations have enabled architects and engineers to push the envelope of design, creating structures that are not only functional but also visually astounding.

The Arc de Triomphe is one of the world’s most instantly-recognisable monuments. While it’s not the largest arch in the world, it’s certainly among the most famous, and is located at the west end of the Avenue des Champs-Élysées in the middle of the Place Charles de Gaulle. It was commissioned by Napoleon and designed and partly built by architect Jean Chalgrin in 1806. On his death in 1811, the construction was taken over by Jean-Nicholas Huyot but due to a complex political landscape, it wasn’t completed until 1836. Inspired by the Arch of Titus in Rome, it’s 50 metres high and was once the world’s tallest triumphal arch.

The Monumento a la Revolución in Mexico City’s famous Plaza de la República is a challenger for the title of world’s biggest arch. The building was intended to be the Federal Legislative Palace during the presidency of Porfirio Díaz. Construction started in 1910 but was stopped due to the outbreak of the Mexican Revolution. Following the revolution, the incomplete palace was repurposed by architect Carlos Obregón Santacilia into a monument honouring the revolutionary movement. Believed to be the world’s tallest triumphal arch, the copper-domed structure stands 67 metres high and is the final resting place of many of the revolution’s key players, including Francisco ‘Pancho’ Villa.

Thirty years after the worst nuclear disaster in history, when reactor No. 4 at the Nuclear Power Plant in the Ukrainian town of Chernobyl exploded, one of the contenders for the biggest ever arch, and without doubt the largest movable land-based structure ever built, was slid into place over the contaminated site. It was designed to confine the radioactive remains of Chernobyl reactor No. 4 for 100 years, to prevent the release of radioactive materials, and to allow for the reactor’s safe decommissioning. Built at a cost of around $2 billion with funds from over forty nations, the 29,000 tonne NSC is 108 metres high, 162 metres long and has a span of 257 metres.

The Sydney Harbour Bridge is the world’s tallest steel arch bridge – 134 metres from the highest point to the water level – and one of the most iconic structures in the world. Believed to be loosely based on New York’s Hell Gate Bridge and the Tyne Bridge linking Newcastle Upon Tyne and Gateshead in the northeast of England, it crosses Port Jackson, or as most of the world knows it, Sydney Harbour. It was designed and built by Middlesbrough-based company Dorman Long under the direction of John Bradfield from the New South Wales Department of Public Works, and opened in March 1932.

The main span, while not actually the largest arch in the world but certainly one of the most famous, measures 503 metres and weighs 39,000 tonnes. The bridge is held together by around six million hand-driven rivets, some of which weigh over three kilograms each!

The world’s longest span arch bridge and a contender for the world’s largest arch, the Longtan Tianhu Bridge in China’s Guangxi Zhuang Autonomous Region is a staggering feat of engineering. Completed in 2024, the main span over the Hongshui River is 600 metres long and the total length of the four-lane, 26-metre wide road bridge is just over 2,500 metres.

Unlike most span arch bridges which are constructed primarily of steel, the Longtan Tianhu Bridge is made from steel-reinforced concrete, an innovative approach designed to handle the immense forces acting on such a long span.

The Gateway Arch, formerly known as the St. Louis Arch, is the biggest arch in the world. Standing 192 metres tall, it’s also thought to be the tallest human-made monument in the Western Hemisphere. Technically a weighted catenary arch, it was designed by Finnish-American architect Eero Saarinen in the 1950s with construction starting in 1963. It was completed two years later at a cost of $13 million (the equivalent of around $115 million today). The stainless steel arch on the west bank of the Mississippi River in St. Louis, Missouri, symbolises the westward expansion of the United States and is believed to be the largest ever arch, an architectural marvel of the modern age.