" In 1954, peace talks were being held in Geneva at the Hotel des Bergues (now the Four Seasons). Attending those peace talks was the last Emperor of Vietnam, Bao Dai. As history would show, the peace talks were not that successful, and neither was Emperor Bao Dai who was later exiled in 1955. But if there was one thing that could be said about him, Bao Dai had expensive tastes.
Frustrated with how the talks were going, Bao Dai stepped outside to get some fresh air. On a whim, he left the Hotel des Bergues and walked across the street to the respected watch retailer, Philippe Beguin, and asked for the most expensive Rolex he had."
Source: The Recovering Legalist
And then this

Source: Alexandre Landre
Hence the answer is " 22 rue du Mont Blanc "