High rise green: highest in the world

The city of Rotterdam wants to attract 20,000 new dwellers to its inner-city. High-rise is one of the seven strategies suggested by the municipality. Looking at city dwellers nowadays, the lack of families is obvious. How could high-rise not only be attractive to dinkies (double-income-no-kids) but also to families? I would say: by not only stacking pre-cast concrete, but stacking some green space as well. As a matter of fact, Rotterdam could strive for the highest green in the world!

The city of Rotterdam used to have the highest skyscraper in Europe: office building Het Witte Huis at Geldersekade (1898, 43 m). Today, the battle for height is fought in a different part of the world. Dubai's Burj Khalifa (828 m) is now challenged by Azerbeijan and Saudi-Arabia, who intend to spend a vast amount of petrol dollars on skyscrapers higher than kilometre.

Within the Netherlands, Rotterdam can still be considered a skycraper city: half of the top-15 tall buildings is located in Rotterdam, including the top-3: Maastower (165 m), New Orleans (158 m) and the office-block next to Rotterdam central station (151 m). Further down the list are Montevideo (140 m), the Millenniumtower (132 m), The Red Apple (127 m) and the World Port Center (123 m).

We stack living rooms, bedrooms, bath rooms, toilets, service closets, parking spaces, meeting rooms and workspaces. By now, we have stacked more workingspaces than we have jobs. What we don't stack is the one thing that is hard to find in Rotterdam: collective green space. An orchard with apple-trees. A fresh lawn. A palm tree. Or two, enabling a hammock in-between. Let's not compete with Jeddah and Baku for the highest floor. In Rotterdam we could make the highest green: the highest orchard, the highest palm trees, the highest hanging hammock in the world!

Currently, the highest collective green in the world is General Sherman: a giant sequoia in California (84 m). Taller trees have been discovered, but their locations are kept a secret. But even 84 m already leaves us with a problem: the buildings surrounding Stadhuisplein are only 20 m tall. If we would only transform the rooftop into a garden, it would not be the highest green in the world.

No worries. Let's have a look at high-rise theory. The tip is usually measured starting from the pavement in front of the main entrance. If we would kick down the pavement about 64 m into the ground, Rotterdam would have the highest green space in the world. Or we could just wait. The pavement sinks an average of 2 cm per annum because of the soft layers of soil underneath. In other words, in about 3,200 years, the pavement will have sunken 64 m and Rotterdam could have the highest green in the world! After all, size matters...