Did you know that there’s a secret garage that houses hundreds of lovingly preserved Audi models from across history?

Within a four-storey nondescript building in Ingolstadt, Germany—where Audi global headquarters is also located—lies a secret garage full of Audi vehicles. Set up in 2001, Audi Tradition is a private garage that houses about 500 historic vehicles, all representing the iconic milestones in the brand’s history. Here are four cool facts about this treasure trove:

Unfortunately, this means that Audi Tradition is not open to the public—you can’t just walk in and check out the awesome historical cars at Audi Tradition. However, some models are sometimes loaned out for museum displays.

Ralf Friese and his colleague, Peter Kober, take care of Audi Tradition. Peter sources for cars that were made before 1945 while Ralf collects vehicles from 1945 up to the present day. Ralf, who has been working at the garage for ten years, is a “living encyclopaedia” who is able to rattle off cool facts about the brand’s cars off the top of his head, such as when the different models were introduced. He has even written two books on the Audi models released since 1965.

Among Ralf’s favourite classics at the garage are the Horch 850 Pullman and the 1919 Audi Type C. The pristinely maintained Horch 850 Pullman was considered a luxury must-have in the 1930s as it cost the equivalent of a house back then. It takes three trained technicians 20 minutes to open and close its retractable roof. The 1919 Audi Type C was introduced in 1912 and emerged victorious in the Austrian Alpine Rally for three consecutive years. Some of the vintage vehicles are still road-worthy. In Ingolstadt, Audi Sport Ambassador and Mediacorp Artiste Tay Ping Hui had the rare opportunity to meet Ralf and drive the Audi quattro, one of the world’s most well-known cult cars.

One entire floor of the building is devoted to Audi’s rally and race cars, with all the past race cars of Le Mans races present. There are serious winners here, such as the victorious cars of rally champions like racing sensation Michèle Mouton, who, in 1981, was the first ever female to win a World Rally Championship round. Another floor inside Audi Tradition is dedicated to recent concept cars, such as the Audi TT Coupé and Audi Pikes Peak quattro, which predates the Audi Q7.