London’s Westminster Abbey, one of the UK’s most visited tourist attractions, is undergoing work on a new museum, marking the first addition to the visitor experience at the historic site since 1745.

The £23m (US$32m, €26m) museum, named the Queen’s Diamond Jubilee Galleries, will be located inside the triforium – a loft-like space above the arches of the nave of a church – some 70ft (21m) above the Abbey's floor.

The triforium has never been open to the public and has generally been used for storage and by the occasional TV camera operator. The poet John Betjeman described the view of the Abbey from the triforium as the “best view in Europe”.

To provide access to the triforium galleries, a slim tower – constructed from stone, glass, lead and oak – is being built in a courtyard at Poet’s Corner. The tower, inspired by the Gothic architecture of the Abbey, was designed by conservation and restoration architect Ptolemy Dean, who is Surveyor of the Fabric at the Abbey.

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.

Inside the Queen’s Diamond Jubilee Galleries, which offer views through the windows to the Houses of Parliament, more than 300 artefacts will be on display, with exhibition design by MUMA (McInnes Usher McKnight Architects). The space will be 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.

The new museum will open in June. It’s the biggest undertaking at the Abbey since Nicholas Hawksmoor’s West Towers, which opened in 1745.

More than 95 per cent of the money for the project has been raised from private donations, with HRH The Prince of Wales leading the fundraising campaign. The Abbey, which received 1.8 million visitors in 2016, holds 28 services every week. Members of the public can donate and sign an online guest book at the website www.westminster-abbey-galleries.org.