When construction workers start on a building project, they never know what they might find. While what lies under a building or behind its walls is often just debris, on rare occasions, incredible treasures and amazing artefacts are discovered... Read on to see the finest finds discovered hidden on construction sites around the world.

All dollar amounts in US dollars and currency conversions correct for the time.

This Roman drinking vessel was part of the so-called Hildesheim Treasure, discovered by Prussian soldiers when they were expanding their shooting range at Hildesheim, in what's now Germany, back in 1868. The trove consisted of more than 70 silver items for eating and drinking and is thought to date back to the reign of Emperor Augustus, around the birth of Christ.

One of the drinking vessels was identified as having belonged to a high-ranking military official called Bochus. 

In 1903, Norwegian farmer Oskar Rom discovered a Viking-era ship after he dug into an ancient burial mound on his land. It took 21 years for archaeologists to prepare and restore the vessel, as it needed to dry out fully before being put together. The reconstruction remains on show at the Viking Ship Museum in Oslo.

Also found on the ship were the skeletal remains of two women and various animals and other artefacts, including bedposts and a cart.

A mechanical digger operator discovered the 8th-century Anglian York Helmet when construction started on a shopping centre in York, England, in 1982. It's one of only three complete examples from the Anglian period found in England and bears Anglo-Saxon and Irish influences.

On the crest is an inscription in Latin, which translates as: "In the name of our Lord Jesus Christ, the Holy Spirit and God; and to all we say amen. Oshere". It's thought that Oshere was the name of its owner.

The Roman-era Lopen Mosaic was unceremoniously uncovered by a bulldozer during the building of an access road in the tiny village of Lopen in Somerset, England, in 2001. Featuring a pattern of squares, wine vessels, leaves and a dolphin, experts believe it was laid as part of a Roman villa belonging to a wealthy landowner in the 4th century BC.

Speaking at the time, English Heritage's chief archaeologist Dr David Miles said it was an expensive design, "the equivalent of a Persian carpet". 

Roman marbles are just some of the artefacts recovered during the decades-long construction of a new underground rail line in the Italian capital Rome. Since work began in 2000, everything from an iron spearhead to a delicate perfume bottle and bronze fish hooks have been uncovered.

Commuters can admire many of the treasures on a daily basis in the San Giovanni metro station, where they've been on display since 2017. 

The remains of an Iron Age chariot burial were found at Newbridge, Scotland ahead of building work starting on the Edinburgh Interchange in 2001. After careful recovery of the wheels, which were lifted out in soil blocks for full excavation back in a lab, the preserved wood was radiocarbon dated to between 475-380 BC – making it the oldest chariot burial in Britain.

This reconstruction, pictured, was built in 2007 by Robert Hurford several years after the chariot's discovery. 

In 1890, the municipal art collection in the German city of Neubrandenburg comprised more than 10,000 pictures, sculptures and pieces of porcelain housed in the former ducal palace. But the palace burned down and collapsed during World War II, and it was only during building work on an underground car park in 2006 that parts of the porcelain collection were found again.

Sixteen figures were restored with the help of porcelain manufacturer Meissen. 

This stone cup was one of the historic items found at Shuafat, on the road from Jerusalem to the West Bank city of Ramallah, ahead of the construction of a light railway in 2007. Coins and ceramic art were also found during excavations at the site of what was thought to be an ancient Jewish village, which existed between 70-130 AD, along with a hammam and three ritual bathing pools. 

Guests at Belfast's Merchant Hotel may be surprised to see a series of small ceramic eggs on show as they enter the five-star establishment. The 30 eggs were found alongside fragments of crockery from the 17th century in 2008, ahead of a £16.5 million ($32.7m) refurbishment to create a lower ground-floor spa.

Experts believe these curiosities are likely to have been replica "dummy eggs" that were put in coops to encourage hens to lay.

Discovered somewhat after the fact, English King Richard III eventually received a ceremonial burial in 2015 – three years after his bones were found under a car park in Leicester and more than 500 years after his death. Richard III died while facing the forces of Henry Tudor during 1485's Battle of Bosworth Field, and his body was hastily buried at what was then Greyfriars Church.

His body was discovered by archaeologists in 2012, and it was later decided he should be reburied in Leicester Cathedral. 

Pieces of ancient pottery, iron tools, and jewellery were found at a construction site in Dakar after floods hit the Senegalese capital in 2012. Items uncovered when rain washed away the sand included iron scoria, small stones including blades, and perforated shells used as jewellery.

Speaking to the BBC at the time of the discovery, local academic Alioune Dème said the items could date back to between 2,000 and 7,000 BC. 

This fragment of a Roman ceramic beaker was unearthed during construction work at Bloomberg Place in London's financial district in 2013. Believed to date back to the 1st century AD, it was one of about 10,000 accessioned items discovered at the site, which archaeologists nicknamed the "Pompeii of the North".

Pottery, coins, an amber gladiator amulet, and incredibly well-preserved wooden structures from the same era were also found.

In 2016, some 10,000 cultural relics were found during the construction of the Beijing administrative centre in Tongzhou, a suburb of the Chinese capital. The finds helped date the history of Tongzhou back to China's Warring States Period of 475-221 AD.

The discovery of more than 1,000 tombs and an ancient city from the Han Dynasty (206 BC-220 AD) also helped establish that the area had a large population 2,000 years ago. 

A Celtic pot of gold was found ahead of the building of a machinery hall in Traun, near the Austrian city of Linz, in 2016. The 44 gold coins are thought to have been made during the Iron Age in the region now known as Bohemia, in the present-day Czech Republic, and are likely to have ended up in Austria through trade.

The coins were found lying close together, suggesting they were once in a bag or other container. 

The remains of a 19th-century lime schooner were discovered during construction work at Boston's Seaport District in 2016. Crews working on the site at 121 Seaport Boulevard found the hull of a large ship preserved in the clay of the South Boston Flats, once a tidal mudflat that would have been dry at low tide and submerged at high tide.

Many casks and barrels filled with lime, an important component in mortar, were also found at the site.

A 600-year-old Buddha was discovered during renovations at Hongmen reservoir in China's eastern Jiangxi Province in 2017. The head of the statue emerged after water levels dropped by more than 32 feet (10 metres) during work on a hydropower gate.

It's believed the statue could date back to the early Ming Dynasty, which lasted from 1368-1644.

Workers demolishing the abandoned Cressoni Theatre in Como, near Milan in Italy, stumbled across a literal pot of gold when they found a soapstone amphora of 300 coins dating back to the Roman imperial era in 2018.

The coins were stacked in rolls, and coin expert Maria Grazia Facchinetti said whoever placed the jar there had "buried it in such a way that in case of danger they could go and retrieve it". The coins date back to 474 AD. 

A 17th-century oil painting was found hidden behind a wall by workers converting a Paris office into a luxury boutique for fashion brand Oscar de la Renta in January 2019. The artwork is thought to have been created during the reign of King Louis XIV in 1674 by Arnould de Vuez, a leading artist of the day, and shows the Marquis of Nointel, Louis XIV’s ambassador to the Ottoman empire, riding to Jerusalem.

Experts now believe the painting may have been concealed there to hide it from Nazi looters. 

In 2019, construction workers digging on a site in Highlands Ranch just south of Denver made a prehistoric discovery: the partial skeleton of an adult triceratops. The dinosaur fossils, dated at 68 million years old, were uncovered by palaeontologists from the Denver Museum of Nature & Science.

The Denver area is a bit of a dino hotspot, particularly for triceratops. The fossils are now being studied by experts at the Denver Museum of Nature, and some are on display there.

In 1982, author Byron Preiss released a book called The Secret. It contained 12 puzzles, each featuring a poem that had to be paired with a painting, which would lead to a treasure 'casque' containing a key buried in a park. Two had already been found.

In 2019, Jason Krupat believed he'd figured out that one was buried in Langone Park in Boston. He visited the park and was shocked to see construction work underway. "I got up the courage to walk onto the site and find the foreman, and I said, 'You’re going to think this is crazy, but I think there’s buried treasure in this park,'" Krupat told the Boston Globe.

His hunch was correct, and the discovery was filmed for TV show Expedition Unknown, which had highlighted the still-buried treasures in a previous episode. The 'casque' contained a key, which was later exchanged for a green gemstone called a peridot, valued at $1,000 (£712), in a ceremony in New York attended by Preiss's widow (he died in 2005).

In 2019, builders on the Gold Coast in Queensland, Australia, dug up a number of tightly sealed containers on a site they were clearing at Runaway Bay. More and more packages revealed themselves and concealed inside lay AU$200,000 ($152k/£100k) worth of old bank notes phased out of circulation in 1996.

Real estate records show the plot was likely vacant in the 1980s, making it a possible hiding spot for the Gold Coast bank robber Brenden Abbott, who's currently still serving a 23-year prison sentence.

In June 2020, road resurfacing in Poland led archaeologists to a hoard of 507 silver coins dating back to the 17th century. The collection includes denominations from across Europe, decorated with the likes of Charles X Gustav of Sweden (pictured) and Frederick William I of Prussia.

Metal detectorists unearthed the coins in the city of Ełk, located along a major trading route spanning from north-eastern Poland to Königsberg, the historic Prussian name for what is now Kaliningrad in Russia.

Also in June 2020, 271 Aboriginal artefacts were discovered at the Griffith Base Hospital redevelopment site in New South Wales, Australia. It's thought some of the small stones used as cutting and scraping tools – known as bipolar flakes – had been there for thousands of years, which suggests that a camp may have existed on the site.

Some tools are believed to have been transported there through the moving of gravel to the construction site over the years. The multimillion-dollar hospital development was paused while the tools were fully excavated from the site.

In 2022, Oxburgh Hall in Norfolk, England, underwent a £6 million ($7.8m) renovation to repair the roof of the Tudor house, which many consider a treasure in its own right. But when a builder working on the project spotted a shimmer of gold, a number of hidden treasures were uncovered.

A rare 15th-century illuminated manuscript was discovered, as well as rats' nests packed with 200 individual samples of expensive textiles dating back to the 16th and 18th centuries. Handwritten music from the 16th century and chocolates from World War II were also revealed.

A tapas bar in Seville, Spain, was discovered to be the former home of a 12th-century Islamic bathhouse during renovations in July 2022. Local legend had always suggested that the Cervercería Giralda bar’s site could have been an ancient hammam, but many put its incredible Islamic revival style down to a 1920s architect, Vicente Traver, rather than authentic decoration created around 900 years ago.

Once archaeologists uncovered the star-shaped skylights, similar to those found at the Arab Baths of Ronda (pictured), also in Spain, they knew they had discovered genuine Almohad Caliphate empire architecture. 

In September 2022, authorities working on renovations in the vicinity of the Srisailam Temple in Andhra Pradesh, India came across more than stone and rubble. Workers found 264 silver coins, a copper coin, and three copper plates with inscriptions, known as tamra patras. The coins were dated between 1800 and 1913, an era of British rule in India.

The site has proven to be quite the treasure trove, as just one month later a brass box was unearthed containing handfuls of gold and silver coins, as well as three gold rings. Other treasures previously found during renovations include five gold bangles, more than 170 coins, and an array of kitchenware.

Another car park discovery was made in Manchester, England, in January 2021 when the area was cleared for a public park. During the removal process, the remnants of a Victorian bathhouse that first opened in 1857 were unearthed. Experts had expected to find remains of Mayfield Baths (pictured) on the plot, but the extraordinary condition of the tiling came as a shock after the area suffered heavy bombing during World War II.

The bathhouse’s two pools – one for men and one for women – would have been an essential amenity for textile workers in the area, who lived in cramped and unsanitary conditions. The recovered tiles are included in designs for the £1.4 billion ($1.95bn) regeneration of the neighbourhood.

Now find out more about the ordinary people who stumbled upon extraordinary amounts of gold