The priceless art collection which Holkham Hall was built to display in the 18th century is being sent back to Italy for a major new exhibition.

In 1712, a boisterous teenager named Thomas Coke was sent to Europe by his wealthy family to improve his education.

He returned six years later as a cultured gentleman, having amassed an extraordinary collection of art and literature during his Grand Tour – and then he built Holkham Hall to showcase those treasures.

Now part of the priceless collection of the 1st Earl of Leicester is being sent back to Italy for a major exhibition which reveals the nobleman's passion for Italian art and his fascination with ancient civilisations.

A unique 17th-century manuscript, valuable paintings and classical sculptures will be among the 60 items loaned from the north Norfolk estate to the Museo dell'Accademia Etrusca e dell a Città di Cortona (MAEC) in Tuscany.

Many will be returning to Italy for the first time since they were bought by Holkham's founder 300 years earlier.

Dr Suzanne Reynolds, curator of manuscripts and printed books at the estate, said: 'This is an extraordinarily important collection which is completely integral to Holkham Hall – and it is a very rare survival of a house that was built to house a collection, and whose collection is more or less intact.

'One of the things the exhibition will focus on is the Grand Tour, and to explain the genesis of where this collection came from. The notion of the Grand Tour became much more recreational during the 18th century, but Thomas Coke's was a very serious cultural enterprise.'

A central thread of the exhibition will be a series of objects which highlight Coke's pivotal role in widening the understanding of the ancient pre-Roman civilisation of the Etruscans.

In 1719, he purchased a manuscript called De Etruria Regali, a monumental history of the Etruscan people written 100 years earlier by Thomas Dempster, a Scottish academic.

The work remained unpublished during Dempster's lifetime and survived only as an original hand-written document. So its new owner set about publishing it, adding a substantial volume of illustrations to the printed edition.

It was the first time a work of ancient history was based on the evidence of surviving artefacts and objects, rather than purely on written sources – laying the foundation for modern archaeology.

The importance of Coke's role in the publication was only fully understood in 2007 when Dr Reynolds discovered an accounts ledger which includes payments to commissioned artists and engravers.

The exhibition will also feature some original drawings and copper plates for the illustrations which were found in Holkham Hall's attics by the 5th Earl of Leicester in 1964.

Dr Reynolds said: 'It is a landmark publication because, rather than just writing history based on the works of other historians, it sought out artefacts from ancient history and incorporates them.

'Finding these accounts was the key to unlocking how it all fits together – who the artists were, how much Thomas Coke spent, and how involved he was in the process.

'When he decided to publish this book, he was thinking of a shared history and a shared culture across borders. That is what we are doing again with this new collaboration across borders.'

The exhibition runs from March 21 to July 31, and will also include exhibits from the Uffizi museums in Florence, the Vatican Museums, and the British Museum in London.