An invisible €171m renovation: Dutch royal palace reopens after five-year-long underground project

The 17th-century Paleis Het Loo (left) has added a 5,000 sq. m underground extension (right) that includes a new entrance hall, restaurants and exhibition spaces Photo: Paleis Het Loo / Simon Menges
Sometimes called the “Versailles of the North”, the Dutch royal palace of Het Loo has been radically transformed after a five-year-long, €171m renovation, including an “invisible” underground extension of around 5,000 sq. m.
The palace was built in 1686 as a royal hunting lodge for King William III and Queen Mary on the outskirts of the city of Apeldoorn in the heart of the Netherlands. It remained a summer retreat for the House of Orange well into the 20th century. Queen Wilhelmina stayed there after the Second World War until her death in 1962.
Since 1984, Paleis Het Loo has been open to the public as an independent national museum, though the royal family have still used it from time to time for official ceremonies. The museum aims to immerse visitors in the history of the royal house and its extensive art collections. The palace’s treasures include a grand staircase and authentic period rooms packed with wall paintings, tapestries and countless artefacts that reflect on Dutch history.
The grand staircase at Paleis Het Loo Photo: Maarten Albrecht
By 2018, the 17th-century building was in need of a thorough renovation. Most pressingly, they needed to strip out around 4,300 sq. m of asbestos, modernise the visitor facilities and update almost all of the palace’s technical systems.
Museum leaders seized the opportunity to enlarge the complex with a new main entrance and more space for temporary exhibitions. But they had one important condition for prospective architects of the redesign: the new space would have to be situated entirely underground and out of sight, beneath the vast courtyard in front of the palace.
Five Dutch architectural firms were shortlisted for the project from a public tender. From among them, the Rotterdam-based KAAN Architecten emerged victorious. They won their spurs in 2007 with the impressive transformation of a famous monumental building in Amsterdam into the City Archives and, more recently, the minimalist makeover of the Royal Museum of Fine Arts in Antwerp, which was completed in 2022.
Dikkie Scipio, the project leader, says KAAN Architecten looked hard for an architectural solution that would not detract in any way from the splendour of the palace. She describes the concept as an “invisible intervention”.
The palace's picture gallery Photo: Paleis Het Loo
Michel van Maarseveen, the director of Het Loo, was delighted with the architectural firm’s proposal. “KAAN Architecten presented a project which coincided exactly with our wishes while also respecting the historical palace complex in every regard,” he says. “The underground extension has an aura that fits the building.”
Het Loo’s historic forecourt previously consisted of four large parterres (ornamental gardens) which formed an oval and were flanked by the side wings of the palace. KAAN’s project removed the parterres, making way for an extension several metres below the surface. The grassy lawns have been replaced by expanses of glass which are roughly the same size. They are lined with natural stone edging which allow daylight to penetrate freely into the newly-created spaces underneath. The palace itself is reflected in the glass and the 4cm layer of water that now covers it, hinting at the fountains and waterworks for which Het Loo is famous.
Closer to the palace, the flight of steps in front of the corps de logis (the main central block of the palace) has been refurbished by removing and then carefully replacing each stone.
Another architectural challenge was providing entrances to the new underground reception hall, known as the Grand Foyer, which did not disrupt the prospect of the open square in front of the palace. Scipio solved this by placing them at the ends of the outer east and west wings of the palace, in new corner pavilions which take the form of large lanterns. After entering through one of the lantern structures, visitors converge in a wide lateral corridor before turning into the Grand Foyer, the shape of which is inspired by the original plan of the corps de logis, now many times enlarged.
The original ornamental gardens of Paleis Het Loo’s central courtyard have been replaced by glass skylights above the 5,000 sq. m underground extension
Photo: Simon Menges
From this marble-clad space there will be access to the palace and renovated east wing as well as the west wing, which now features a “Junior Palace” for younger visitors. The Grand Foyer accommodates reception desks, a museum shop and restaurants, with room for temporary exhibitions beyond. This fundamental reshaping of Het Loo has been driven principally by new ideas about museum display.
The substantial programme of works began early in 2018. Experts gathered from far and wide to restore the palace to its former glory: the walls were rehung, ceiling paintings restored, 17th-century floors brought to light, countless tapestries repaired if not actually rewoven, chandeliers reassembled, and various rooms reordered to prepare them for the display of the enormous royal art collection.
For years the main section of Het Loo was inaccessible, though the stables and the park remained open to the public. The palace finally reopened its doors in 2022, reaffirming its role as one of the four most important Dutch art collections.
The stables at Paleis Het Loo Photo: Paleis Het Loo
The east wing has been completely restored and includes a large exhibition on the history of the Dutch royal house from William III and Mary down to Queen Wilhelmina. The new exhibition was designed by the Dutch firm Kossmanndejong (KDJ), while the main lines of the restoration work were entrusted to another Dutch company, Van Hoogevest Architecten, in collaboration with Museum Het Loo. All this was completed in advance of the final stage of the project, KAAN Architecten’s extension, which opened on 22 April.
Scipio insists that no reference is intended to I.M. Pei’s famous glass pyramid entrance in the central courtyard of the Louvre in Paris. “The conditions at the Louvre are completely different,” she says. “It is in the heart of a city and there are no waterworks involved.”

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