China has consistently surprised us. When I returned from the United States many years ago, it was unimaginable that we would end up where we are now. What China has achieved defies all logic. I credit this to the hard work and enterprising spirit of the Chinese people.

When we started out, we were among the first. Beijing had no and Shanghai had very few large buildings. At that time, it was all about building, building, building - and then selling, selling, selling. We were working like a manufacturer. Soon, however, we realized that land was running out in Beijing and Shanghai. So we started keeping our buildings, and managing and renting them out. We became landowners. That was the second act.

Our tenants now are companies like Uber, the taxi service, Meituan.com, China's version of Groupon - and a large number of startups. These companies operate in a modern way, just like their customers: They go on the Internet, look for an offer and take it.

China's economy became more complex. By now there is a large number of small- and medium-sized companies that work quite differently from big, state-owned enterprises. They don't follow any long-term business plan and don't rent office space for years to come. They start out and need an office right away, for a week, a month or half a year, and they want to be among other entrepreneurs like themselves.

Because people along the route had realized that there was demand and quickly organized supply. That's so Chinese. In a well-organized country like Germany, such a problem may not have arisen in the first place, but in China people immediately recognized an opportunity.

I firmly believe that digitalization has only just begun in China. In addition to the taxi, transport, shopping and hotel businesses, many other industries will follow: education, health care, administration, even the legal branch - everything, really. There is still a lot of opportunity in China for the inventive and ambitious ones.

When we started out, we didn't really think that the era of great opportunity would end one day. We were much too busy developing our companies. But in today's China you can build a city, even a mega-city like Beijing or Shanghai, within 10 or 15 years. And then you are done. So in real estate development, the Gründerzeit is over. But that is not the case in other sectors.