The romantic streets of Bonn's historic old city center are a popular tourist destination even without the pink flowering cherry trees. It features cast-iron lanterns, cobblestones, and classic old buildings decorated with stucco.

Cherry blossoms are very sensitive. The first flowers emerge slowly under the protection of the old branches. They do not like rain at all, and frosty night temperatures can easily harm the flowers as well. Since the weather in Bonn has been cooler than usual, the famous blossoms have turned up a bit late this spring.

Fortunately the old cherry trees have been pruned so high that no one can reach the blossoming cherry branches. Otherwise the precious trees would probably be looted by souvenir hunters. At this safe height, the fluffy pink flowers swing in the warm spring breeze.

It is not so easy to get the right perspective on the sea of flowers at a dizzying height. Old fashioned postcards are no longer in demand; the postcard motif is rather sent to friends and family via Facebook, Twitter and Co. There are even special cherry blossom blogs with the most beautiful pictures of these flowers from around the world.

In the northern part of the Old Town, some of the cherry trees are still waiting to bloom. The many thick buds, however, promise particularly lush flowers this year. Historic guided tours to the French-inspired Old Town district are currently very popular with visitors.

The Bonn street, known as Heerstrasse, has become famous for its cherry blossoms worldwide. It has been named one of the 10 most beautiful avenues in the world, and is popular in cherry blossom blogs. Many tourists, mainly from Asia and Australia, follow the blogs regularly in order to find out when is the right time to book tickets for Bonn.

The roads have already been converted to one-way streets, while hundreds of amateur photographers constantly cause congestion in the Old Town. Everyone spontaneously waits and takes picture while crossing the street - spellbound by the beauty of the cherry blossom trees. some even use the old Roman milestone here as a tripod.

These four students have come from the neighboring city of Cologne to take a photograph in front of the pink cherry trees. Selfies with "sakura" branches - as they are known in Japanese - is a trend thats popular among young women. The selfie is immediately forwarded to friends via social media: "It's so romantic!"

The perfect motifs aren't hard to find in Bonn's Old Town. At each corner the cherry trees transform everything into a picturesque setting. The trees are not that old: They were planted in the 1980s.

Now everyone is hoping for mild spring weather. Frosty nights could turn the pretty pink flowers into wilted brown petals. But in April, the weather in Germany tends to be finicky - so a wide range of temperatures are possible.

The celebration of Bonn's sakura blossoms culimates in an annual festival. Stands selling refeshments and nicknacks line the cobble stone streets in the Old Town as crowds push through under the heavenly pick "ceiling." One highlight is the cherry blossom cocktail, which is made with real petals.