Westminster Abbey today (29 May) officially unveiled The Queen’s Diamond Jubilee Galleries for the first time, ahead of the museum’s public opening on 11 June.

The new gallery spaces, which will display 300 treasures from the Abbey’s collection, are hidden inside the building’s triforium, a loft-like space some 52ft (16m) above the Abbey's floor.

The Triforium, unused for centuries and never before open to the public, has been transformed by McInnes Usher McKnight Architects (MUMA) “to allow people to deepen their understanding of a royal church which has been at the centre of the nation for centuries.”

The space is divided into sections, including areas dedicated to Building Westminster Abbey, Worship and Daily Life, Westminster Abbey and the Monarchy and The Abbey and National Memory.

Visitors will be able to browse a wide variety of objects from the Abbey’s collection which will include the 14th-century Liber Regalis – a manuscript that explains the schedule for a coronation service – an ancient altarpiece, a corset belonging to Elizabeth I and artefacts from the reigns of Henry V and VII, guidebooks to the Abbey dating back to 1600, Prince William and Kate Middleton’s marriage license and artist Ralph Heimans’ celebratory Diamond Jubilee portrait of Queen Elizabeth II.

Take a first glimpse inside The Queen's Diamond Jubilee Galleries - set high above the Abbey floor in the medieval triforium and displaying the greatest treasures from the Abbey collection. Opening 11th June https://t.co/3E3gOak6Ll#AbbeyGalleries pic.twitter.com/SOm6Svz0U8

— Westminster Abbey (@wabbey) May 29, 2018

To provide access to the Triforium galleries, a slim tower – constructed from stone, glass, lead and oak – has been built in a courtyard at Poet’s Corner. Named the Weston Tower, the structure’s design has been inspired by the Gothic architecture of the Abbey. Conservation and restoration architect Ptolemy Dean, who is Surveyor of the Fabric at the Abbey, is behind the plans – the first major addition to the Abbey church since 1745.

With a star-shaped footprint that reflects a motif found throughout the 1,000-year-old landmark, the slender tower slots unobtrusively between the Chapter House and Lady Chapel. Inside, a staircase and lift will deliver visitors to the gallery spaces.

“We look forward to welcoming visitors to the Galleries,” said Dr John Hall, dean of Westminster. “The views are breathtaking; the space astonishing; the displays fascinating. The visitor will gain far greater insight into the life and history of the Abbey than ever before. The fulfilment of this vision is a shared achievement with so many people involved. We are profoundly grateful.”

The Queen’s Diamond Jubilee Galleries form the final phase of a 2020 development plan, which set out to offer “a more comprehensive and generous welcome” to the two million people who come annually to the Abbey as worshippers and visitors. The total project cost has been £23m (US$30, €26m), all of which has been met by private donors and trusts.