On a typical block in Hong Kong, thousands of people live on top of each other. Pol Fàbrega thinks about all these people as he looks up at the towering high rises above the streets. And then he thinks about all that space above all these people.
"The square footage here is incredibly expensive," says Fàbrega, staring upwards. "But yet, if you look at Hong Kong from above, it's full of empty rooftops."
It is, he says, a big opportunity for growth.