A project to build a new rail tunnel in London has turned into an archaeologist's dream.

Artefacts dating back thousands of years have been discovered during the construction of the line, known as Crossrail, unearthing layers of the city’s history.

Now, 500 of the most interesting objects are on display at the Museum of London, including a 16th-century bowling ball, ice skates made of animal bones and a Roman pot, which holds cremated remains.

"London really is like a layer cake of history of the city from the Roman levels through the medieval, the only modern period into the more recent centuries," Jay Carver, lead archaeologist for Crossrail, told Al Jazeera.

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The construction of the 42km tunnel, which began eight years ago, is Europe's largest engineering project.

By law, large-scale construction in London must have archaeologists on hand to sift through excavations.

Museum curators and historians are trying to use the project to better understand the way people lived in the past.

“We can use a minute sample, even one tooth, and we can find out where an individual came from, what stresses they were under and how they died," Jackie Keily, curator at the Museum of London, said.

The Crossrail tunnel is due to open in 2018.