Mauritshuis, The Hague. Photo Ronald Tilleman.

No one—from the Mauritshuis's director to fellow journalists attending the press preview last week to Dutch people this writer met in cafés—could resist playing up the Hague museum's track record when it comes to owning celebrated paintings that have inspired bestselling novels. There's Tracy Chevalier's Girl with a Pearl Earring, 1999, based on the Vermeer canvas; Donna Tartt's The Goldfinch, 2013, which sports Carel Fabritius's eponymous panel painting on its cover; and Nina Siegal's The Anatomy Lesson, 2014, which imagines the backstory of Rembrandt's masterpiece The Anatomy Lesson of Dr. Nicolaes Tulp. (Paulus Potter's monumental 1647 painting of a bull remains unclaimed, for anyone looking to pitch a historical novel about farming in 17th-century Holland.)

And no wonder the locals are proud, since the collection boasts some 800 works by Vermeer, Rembrandt, Frans Hals, Hans Holbein, Jan Steen and many other European masters. Moreover, the works are displayed in an elegant townhouse, an example of Classical Dutch architecture, in the center of town adjacent to scenic lake Hofvijver.

The museum reopens tomorrow after a $41-million renovation and expansion by Dutch architect Hans van Heeswijk, who also designed the new entrance to the Van Gogh Museum in Amsterdam, as well as the Hermitage's outpost there. Housed in the former home of Johan Maurits van Nassau-Siegen, a count who governed the Dutch colony in Brazil from 1636-44, the museum now has nearly twice as much floor space and will also be able to mount temporary exhibitions without moving its permanent collection into storage, as was previously required. A library, café and auditorium, not to mention new windows, lighting and modernized climate control and security systems, are also part of the renovation project. The addition, formerly the extension of a private social club that opened in the 1930s and was later used as office space, was acquired by the museum in 2007.

To keep the building time as short as possible, the Mauritshuis spent four and a half years preparing for the expansion. Due to The Hague's geography and position at sealevel, as well as the museum's location across the street from Dutch Parliament, construction was especially complicated. "It was like building next to the White House," Emilie Gordenker, the Mauritshuis's Dutch-American director since 2007, told A.i.A. in one of the somber collection rooms on the museum's second floor. "The cables underneath the building were like spaghetti, but luckily the Dutch are extremely good at these types of engineering challenges." Construction equipment was installed on pontoons in the nearby Hofvijver. Throughout the two-year process, a selection of the Mauritshuis's Dutch Golden Age paintings toured internationally; the Tokyo exhibition of "Masterpieces from the Royal Picture Gallery Mauritshuis" was the most attended museum show in 2012, according to the Art Newspaper.

While discussing the renovation at a press conference, Gordenker mentioned that she banned the word "tunnel" from descriptions of the new below-ground lobby area that connects the original building to the Art Deco one next door. Visitors now enter the museum by way of a glass-enclosed staircase set into the house's gated courtyard. "Before, the entrance was awful, via the servants' quarters. Now you go through a light-filled foyer," said Gordenker.

From there museumgoers can explore the Dutch and Flemish paintings hung in the 16 collection rooms in the original building, or visit the temporary exhibition space in the adjacent wing. The current show, which explores the history of the building-its architecture, interiors and various renovations-as well as background on its original owner, is on view through Jan. 4, 2015. Upcoming exhibitions include highlights from New York's Frick Collection (Feb. 5-May 10, 2015), where Mauritshuis treasures were on view last year; an in-depth look at Rembrandt's painting Saul and David (June 11-Sept. 13, 2015); and a show focusing on self-portraits by Dutch artists (Oct. 8, 2015-Jan. 3, 2016).

The other (mostly cosmetic) changes improve upon the museum's elegant, picturesque nature: woven silk wall coverings in the collection rooms, soft LED lighting and Venetian glass chandeliers, new four-pane windows reminiscent of those original to the house, and exterior masonry restored to the creamy yellow color that was present in 1644, when Maurits returned from Brazil and took up residence in his new home.

Despite its reconfiguration, the museum is still "an intimate jewel box," observed Gordenker. "It really doesn't feel twice as big."