The “ground plane” is an important reference in architecture. The ground is typically where people walk. The ground is where our fabricated buildings meet the earth. And the ground is where our experience of the urban environment–however good or bad it may be–truly takes shape. Often times I feel that we, city dwellers, spend far too much time worrying about the height of buildings and not enough time worry about the ground floor.

But what if there were no clearly defined ground plane? This morning I stumbled upon an interesting book called, Cities Without Ground: A Hong Kong Guidebook. The authors call it “a manifesto for a new theory of urban form.” And the argument is that Hong Kong has developed a unique series of public/private spaces that allow it to function as a fully three-dimensional city. 

Through underground tunnels, above ground walkways, escalators, and other connective infrastructure, Hong Kong is reinventing the way we typically think about cities–both from a user experience and a real estate standpoint. Here’s an excerpt from the Guardian architecture and design blog:

The phenomenon began in the 1960s, when the Hongkong Land company, one of the main developers in the region, built an elevated walkway to connect a luxury hotel to the second storey of an adjacent shopping mall. An insignificant move, perhaps, but it in fact had the effect of changing the rentable values within the building: suddenly the mall’s second floor units could be rented out for more than those at ground level. It entirely recalibrated the vertical logic of real estate value.

Now, you could argue that Hong Kong is a unique place. And it is. Other, less dense cities, have found above and below grade walkways to be a destroyer of urban vibrancy. But in Hong Kong it works and, as many other cities around the world focus their energies on urban intensification, we may find that Hong Kong is indeed a new model for urban form.

Yesterday evening I was reading the Spring Summer Candy GPS Report put out by London-based property developer Candy & Candy. If you’ve never heard of Candy & Candy, then I guess you haven’t been in the market for a £60m apartment. Candy & Candy are the developers behind One Hyde Park in London, which is said to be the world’s most expensive residential development.

But what is interesting about a project like One Hyde Park is that it’s really only possible in a global city, like London, that attracts a massive amount of foreign investment. A project like One Hyde Park is a possibility of globalization, not a result of local employment numbers.

Which is why if you take a look at the Candy GPS report, you’ll see that their interest is in tracking the habits of ultra-high-net-worth-individuals (UHNWIs)–those with wealth exceeding US$30 million. Last year, the world was estimated to contain almost 200,000 of them, with a combined wealth of almost $28 trillion. This number is expected to rise to $40 trillion by 2020.

Now, you may not be in the market for the most expensive apartment in the world, but I thought it would be interesting to talk about where this money is coming from and which cities it’s going into–at least when it comes to real estate.

Last weekend I posted a poll asking readers what they think the “capital of the world” will be in 2050. It was really the 2nd half of a two part poll. The first one asked what people think the capital of the world is today. And the majority of people said New York.

While New York still came out on top in the 2nd poll, the most notable difference is the rise of Chinese cities. Behind New York is Shanghai, Hong Kong and Beijing. And in a way, this order makes sense to me. China would like to see Shanghai on top of Hong Kong, because it’s perceived as being more Chinese (Hong Kong is still too British). But both are still more economically important than Beijing.

Still, my own belief is that China is going to need to go through some structural changes before its cities really have a chance of dethroning New York (or London, depending on your vote in the first poll). And I think it has to do with openness, transparency and freedom. Fred Wilson probably put it best when he said to basically invest in whatever China blocks: