Treasures unearthed by hundreds of archaeologists during the ongoing construction of the controversial HS2 train line have been shown exclusively to the BBC.

The 450,000 objects, which are being held in a secret warehouse, include a possible Roman gladiator's tag, a hand axe that may be more than 40,000 years old and 19th Century gold dentures.

It is an "unprecedented" amount and array of items, which will yield new insights into Britain's past, says the Centre for British Archaeology.

Major building developments in the UK need land to be assessed by archaeologists as part of the planning process, to protect heritage sites.

Since 2018 around 1,000 archaeologists have been involved in 60 digs along the route HS2 is set to take between London to Birmingham.

While the route is not currently scheduled to open until after 2033 due to delays, archaeologists say their fieldwork is largely complete.

The warehouse's location is a closely guarded secret for security purposes. All we can say is that it is in Yorkshire. Inside are shelves and shelves of pallets, loaded with around 7,300 boxes of historic items destined for further research.

The future of many objects, including whether they will stay in storage or be displayed, is still undecided, along with their ownership.

Historic England commended the team for revealing "new and exciting sites spanning over 10,000 years of our past".

But building HS2 has changed the landscape along its route, cutting into fields and communities, and dividing opinion.

Critics, such as Greg Smith, MP for Mid Buckinghamshire, say soaring costs, delays, abandoned villages and damage to the natural and historic environment mean that it is not worth building.

"It should not have cost the taxpayer tens of billions of pounds to build a railway that no-one wants and brings so much destruction," Smith says.

HS2 said in response: "Chief Executive Mark Wild has been clear that overall delivery of HS2 has been unacceptable and he's committed to ending the project's cycle of cost increases and delays."

"Our specialist archaeology team and contractors have carefully excavated numerous sites and have shown care and respect throughout this work."

"Whether HS2 is a good or bad thing is debatable, but I tell you what, if they built the railway and they didn't do the archaeology that would be more tragic," said historian Graham Evans, who chairs the Northamptonshire Battlefields Society.

The store holds showstoppers such as Roman statue heads and a gold 'three lions' pendant from the 13th-14th Century.

On the ground in one area is a bubble-wrapped empty coffin dating to 1799, with a smaller one next to it wrapped in masking tape - sobering reminders that this store is a snapshot of real lives once lived.

Some of the objects discovered have already been shown to the public.

We have picked out six that have never been on display. You can see where they were found on the HS2 route map below - then scroll further down to see the objects and read about their history.

Experts think this is more than 40,000 years old and was made by Neanderthals or an earlier species of human.

Found in the Edgcote area in Northamptonshire, it has a sharp edge likely designed for butchering animals.

Hand axes were held in the palm rather than attached to a wooden handle.

"There is something tactile about it when you hold it," said Dr Sara Machin, the finds lead for Access +, the consortium of archaeologists in charge of this project. "Even now it fits snugly in my hand."

The small piece of carved thin bone bears an inscription. Experts would expect it to read if complete: "DOMINE VICTOR VINCAS FELIX" or "Lord Victor, may you win and be lucky."

Discovered in Northamptonshire, Machin says it could have belonged to an active or former Roman gladiator, or even be a spectator's souvenir, even though there is no evidence of an arena or circus space in that part of the country.

It was recovered from a large pottery vessel containing cremated human remains, with an X on the lid.

Dr John Pearce Reader in Archaeology at Kings College University said that a link to a gladiator was possible, but added that "with more forensic analysis of the burial, a different story may come to light".

Thought to be made from a cattle femur, this decorated Anglo-Saxon spindle whorl, used to provide weight while spinning yarn, was unearthed from farmland near Bishopstone, Buckinghamshire.

"It's a very interesting piece of evidence of textile advancements in the Anglo-Saxon period," said Willow Major, a post-excavation assistant.

Its polished surface leads her to believe it got a lot of use and was very dear to someone, she said, adding that interestingly, the ring and dot motif had been found on spinning tools from the much earlier Iron age.

A tiny polished die recovered from a deserted medieval village in Lower Radbourne, Warwickshire, resembles modern ones, but with a different numbering format.

Its imperfections, with one side longer than the others, stand it in contrast with today's mass-produced dice.

This complete figurine of a seated pug dog in plain white-glazed porcelain with black details was found in the grave of an unnamed female at St James' Gardens in Euston.

It is thought to have been made in the Derby porcelain factory around 1770-1800.

"Every box has a surprise," Machin said as she unwrapped perhaps the most bizarre item here, thought to be from the 19th Century: a set of lower gold dentures found at St Mary's Old Church in Stoke Mandeville.

It contains six teeth and has a number stamped on the inside.

"These are objects, but they all relate to people," Machin said. "It's all about the people who lived in these areas going back thousands of years and we can start writing the stories about their lives and what they can tell us."

"The scale is what makes it so extraordinary," Neil Redfern from the Council for British Archaeology says comparing HS2 to other big development projects.

"But it is the length of the scheme and the landscapes and places that HS2 passed through that make the collection of sites and material so interesting. The research potential from this material is remarkable."

He believes that the finds could help people understand wider landscape change now and in the past.

To dig deeper into these stories, archaeologists are now entering the second phase of works, including further condition, cleaning and conservation checks.

More plans are afoot to show the objects. Artefacts from the Wendover Saxon cemetery, where 122 graves were unearthed, will soon go on display for the first time at a Discover Bucks Museum exhibition.

However, the future of other items is less clear.

A spokesperson for HS2 explained that under English property law, archaeological and historical objects found during the works will either belong to the government or landowners.

"Occasionally landowners may wish to retain title to objects, in which case they will be returned to their care," said the spokesperson.

Charlotte Self, archive manager for the project said she and her team were asking landowners to donate them where possible, so people around the route could enjoy them.

"I would love to see the majority of these items deposited with the local museums from near where they were found," she said.

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