The distinctive red railway structure linking Edinburgh and Fife could join a select group of sites across the world, including the Taj Mahal, the Grand Canyon and the Great Wall of China, if the bid is successful. Source: Press Association.
Scotland is home to five of the 28 UK World Heritage sites, including the island of St Kilda and Edinburgh's Old and New Towns.
Stonehenge, the Tower of London, and the Jurassic Coast have also been awarded the sought-after status.
The bridge has been nominated by UK Culture Secretary Maria Miller and the bid will now be considered by the Unesco World Heritage Committee.
Ms Miller said: "World heritage sites attract tourists from all over the world and Britain has some extraordinary places that have yet to be recognised by Unesco.
"If the Forth Bridge bid is successful in achieving such prestigious international recognition, then Britain will have yet another iconic place by which to attract tourists to our shores."
At the peak of construction more than four and a half thousand workers laboured on the 124-year-old bridge.
The first major British construction to be made of steel, it carries trains more than a mile and a half across the Forth.
Scottish Secretary Alistair Carmichael said: "The Forth Bridge is an excellent example of the UK's rich culture and heritage and proudly symbolises Scotland's place in the world as pioneers of construction.
"Inscription as a World Heritage site is an important accolade, achieving this recognition will be tremendous news for Scotland and a fitting tribute to all of the people who have contributed to the building, maintenance and restoration of the bridge in its 124 year history."
Scotland's Culture Secretary Fiona Hyslop said: "The Forth Bridge is an iconic symbol of technical creativity and engineering excellence.
"As one of the world's most recognisable landmarks the bridge not only connects communities in a practical sense, but also connects those who admire its design with Scotland's proud industrial and cultural heritage."
Preparation for the bid was overseen by the Forth Bridge World Heritage Steering Group of the Forth Bridges Forum, which includes numerous partners in the area surrounding the bridge.
Unesco is expected to make a final decision on the nomination next year.
UNESCO World Heritage Sites 2013
Forth Bridge to get World Heritage status?
Levuka, with its low line of buildings set among coconut and mango trees along a beach front, was the first colonial capital of Fiji, ceded to the British in 1874. From the 19th century is became a centre of commercial activity by Americans and Europeans who built warehouses, port facilities, shops, residences and religious buildings. It is a rare example of a late colonial port town influenced by the indigenous community which outnumbered foreign settlers.
As the only coastal desert in the world, the Namib Sand Sea consists of extensive dune fields influenced by fog. UNESCO says it covers an area of over three million hectares and a buffer zone of 899,500 hectares, with the "desert dunes formed by the transportation of materials thousands of kilometres from the hinterland that are carried by river, ocean current and wind".
Located on the northern shores of the Black Sea, the Ancient City of Tauric Chersonese features the remains of a city founded by Dorian Greeks in the fifth century BC, including agricultural lands divided into rectangular plots called 'chora'. Until the 15th century, the plots supported vineyards whose production thrived. The site features public building complexes and residential neighbourhoods, early Christian monuments alongside remains from Stone and Bronze Age settlements, and Roman and medieval tower fortifications and water supply systems.
Japan's highest mountain, Mount Fuji stands at 3,776 metres with its beauty rising above villages and tree-fringed sea and lakes, and long inspiring artists and poets. UNESCO says its "representation in Japanese art goes back to the 11th century" and it has become an "internationally recognised icon of Japan".
The town of Al Zubarah is Qatar's largest archaeological site. The now abandoned settlement was once a thriving pearl fishing and trading port and is one of the best preserved examples of an 18th to 19th century merchant town in the Gulf. It was founded by merchants from Kuwait and had trading links across the Indian Ocean, Arabia and Western Asia. A layer of sand blown from the desert has protected the remains of its palaces, mosques, streets, courtyard houses and fishermen’s huts.
China's Honghe Hani Rice Terraces cover 16,603-hectares in Southern Yunnan. UNESCO says the site is marked by "spectacular terraces that cascade down the slopes of the towering Ailao Mountains to the banks of the Hong River". Over the past 1,300 years, the Hani people have developed a complex system of channels to bring water from the forested mountaintops to the terraces. They live in traditional thatched "mushroom" houses in 82 villages between the mountaintop forests and terraces.
These stunning 12 villas and two pleasure gardens are spread across the Tuscan countryside and show the influence of the Medici family over modern European culture. They were built between the 15th and 17th centuries and UNESCO says they represent an "innovative system of rural construction in harmony with nature and dedicated to leisure, the arts and knowledge."
Consisting of 12 sites representing the history and culture of the Koryo Dynasty from the 10th to 14th centuries, Kaesong's UNESCO World Heritage Site includes its palaces, a tomb complex, defensive walls, an astronomical and meteorological observatory and two schools. UNESCO says "the site testifies to the transition from Buddhism to neo-Confucianism in East Asia and to the assimilation of the cultural, spiritual and political values of the states that existed prior to Korea’s unification under the Koryo Dynasty".
The 15th century town of Agadez is known as the gateway to the desert and was a crossroad for the trans-Saharan caravan trade. Its 11 quarters with irregular shapes contain numerous earth dwellings and well-preserved religious buildings, including a 27-metre high minaret made entirely of mud brick - the highest in the world.
The highest mountain ranges on the Eurasian continent meet in the 2.5 million-hectare Tajik National Park. To the east is a high plateaux and to the west, rugged peaks over 7,000 metres high. Rare birds and mammals, such as Marco Polo Argali sheep, Snow Leopards and Siberian Ibex, are sheltered by the park, and it is subject to frequent strong earthquakes.
Set on a hill overlooking the city, the University of Coimbra includes the 12th century Cathedral of Santa Cruz and a number of 16th century colleges. The Joanine Library has rich baroque decor and there is an 18th century Botanical Garden. UNESCO says Coimbra's "specific urban typology as well as its own ceremonial and cultural traditions have been kept alive through the ages".
The Tianshan Mountains in northwest China are one of the largest mountain ranges in the world, covering a total of 606,833 hectares. UNESCO says the mountains have "unique physical geographic features and scenically beautiful areas including spectacular snow and snowy mountains glacier-capped peaks, undisturbed forests and meadows, clear rivers and lakes and red bed canyons." The landscapes contrast with the vast adjacent desert, creating a striking view of hot and cold, dry and wet, desolate and luxuriant environments.
The Carpathian region's 16 tserkvas are churches built of horizontal wooden logs between the 16th and 19th centuries by Eastern Orthodox and Greek Catholic communities. UNESCO says the "tserkvas bear testimony to a distinct building tradition rooted in Orthodox ecclesiastic design interwoven with elements of local tradition" and feature octagonal domes and cupolas.
Mexico's extraordinary landscape of El Pinacate and Gran Desierto de Altar Biosphere Reserve offers sweeping dunes, huge volcanic craters and rich cultural heritage. In the east is the dormant volcanic Pinacate Shield of black and red lava flows and desert pavements, and to the west, the Gran Altar Desert with its ever-changing and varied sand dunes that reach a height of 200 metres can be seen.
This lavish palace is a masterpiece boasting early Persian crafts, rich ornaments dating back to the 19th century and intricate Qajari architecture. Walled Golestan Palace is one of the oldest groups of buildings in Teheran and became the seat of government of the Qajar family, which came into power in 1779 and made Teheran capital of the country. It is built around a beautiful garden featuring pools and planted areas.
Rajasthan's six majestic forts in Chittorgarh, Kumbhalgarh, Sawai Madhopur, Jhalawar, Jaipur and Jaisalmer boast eclectic architecture with major urban centres, palaces and trading centres enclosed within them. UNESCO says "the forts use the natural defences offered by the landscape: hills, deserts, rivers, and dense forests."
Mount Etna is Europe's largest active volcano and one of Italy's most iconic sites. Located on the east coast of Sicily, the most active stratovolcano in the world has an eruptive history that can be traced back 500,000 years. Etna has an accessible range of volcanic features including summit craters, cinder cones, lava flows and the Valle de Bove depression. It's also an unusual spot for skiing!
The monumental water displays of Bergpark Wilhelmshohe are simply stunning. Reservoirs and channels behind a giant statue of Hercules supply water to the complex system of water displays at the site's large Baroque water theatre, grotto, fountains and 350-metre long Grand Cascade. The geyser-like Grand Fountain leaps 50 metres high and the lake and secluded ponds enliven the Romantic garden created in the 18th century by Landgrave Carl of Hesse-Kassel’s great-grandson, Elector Wilhelm I.
The whaling station on the shore of the Strait of Belle, Labrador, Canada, was established by Basque mariners from Spain and France in the 16th century. Gran Baya, as it was called, was used as a base for coastal hunting, butchering and rendering of whale fat by heading to produce oil and storage. It became a major source of whale oil which was exported to Europe to be used for lighting.