A Valentine’s Day decoration in Berlin’s KaDeWe shopping center.

Like the Galeries Lafayette in Paris or Harrods in London, luxury shopping has one main address in Berlin: KaDeWe.

This institution is celebrating its 110th birthday with a sweeping renovation costing hundreds of millions of euros—while the store remains in operation.

It is pronounced “kah-day-vay,” an abbreviation for Kaufhaus des Westens, German for department store of the West. A spokesperson for the developer, Signa, described the KaDeWe renovations as “operating on a beating heart.”

The new concept, developed by Pritzker Prize–winning architect Rem Koolhaas and his OMA studio, might have taken just eight months had they shut down operations entirely. But KaDeWe has annual revenues of close to €400 million (US$492 million), and dropping all staff for nearly a year was not an option, so Signa and the Central Group, which own 49.9 percent and 50.1 percent of the KaDeWe group, respectively, decided to tackle the project piece by piece, and the project, which began in 2016, is expected to take a total of seven years. ULI members were able to see some of the upgrades on a private tour as part of the ULI Europe Conference in February.

The first refreshed areas are already in operation—new stripes of striking marble floors lead you around the women’s luxury fashion brand—store-in-stores like intergalactic runways. In men’s accessories, tenants are set up in futuristic cubicles; much of the store’s floor space is essentially rented to brands, which gives them more control over presentation of their goods and training the staff. KaDeWe has a total of 646,000 square feet (60,000 sq m) of retail space and attracts 50,000 shoppers a day. That number jumps to 100,000 per day during the Christmas season. The street-level window displays were the first, and most visible, parts of the store to be refreshed, shortly after the project began.

Timo Herzberg, chief executive officer of Signa Prime Selection AG, at right above and left below, leads ULI members on a private tour of Signa’s KaDeWe luxury shopping center, which has annual revenues of nearly €400 million (US$492 million).

Signa purchased KaDeWe for US$450 million in 2012 as part of a larger portfolio of luxury fashion retail centers, and estimates its value at US$1.2 billion. The Central Group, which also owns La Rinascente in Italy, in 2015 purchased 50.1 percent of the KaDeWe Group, which includes Alsterhaus in Hamburg and Oberpollinger in Munich.

Unlike the updated retail spaces in Munich, many shopping centers in Berlin have not been refreshed in many years, and that presents a major opportunity for developers.

Kaufhaus des Westens opened in 1907 on Wittenbergplatz, then on the western outskirts of Berlin, delighting German shoppers with fashion straight from Paris and fresh foods from the Mediterranean. The grand architecture from Emil Schaudt was an attraction in and of itself, with light-filled halls and nearly two dozen elevators. During the Nazi regime, the Jewish owners were ousted, and World War II bombing and a plane crash gutted the building, requiring massive reconstruction during the 1950s. After the Berlin Wall went up in 1961, KaDeWe lost many of its employees and its customers but came to represent the wealth of West Germany; after the wall came down in 1989, more than 200,000 people flooded the store daily, hungry for Western goods.

Since online shopping accounts for more and more of their revenue, traditional retailers are focusing more on the consumer experience of visiting a store. Koolhaas’s vision divides the department store into quadrants, each with a separate entrance and a central atrium with staggered escalators. Each quadrant focuses on an individual customer group—classic, experimental, young, and mainstream—and will offer a signature spatial experience, with each floor having its own distinct personality. The existing vaulted rooftop restaurant will be replaced with a new glass facade that extends organically across the entire building, with a view into the kitchen of the gourmet floor.