Evil can also be beautiful. The Coliseum in Rome, for example, a wonderful structure with an awful past. Just think about the bloody gladiator fights there.

The stronger the identity, the more it imprisons, the more it resists expansion, interpretation, renewal, contradiction.

When we went in the late 1990s, Nigeria was still in a dictatorship. So we didn't go with a mission. It started really with a sort of blankness and open-endedness.

I wanted to disconnect from contemporary architecture

When shopping was still connected to the street it was also an intensification and articulation of the street. Now it has become utterly independent - contained, controlled, surveyed.

At that time [90th in Lagos], if you drove through the city, you drove through a foreground that always seemed to be incredibly dramatic and incredibly agonised - smoking, burning, incredible compression. In the first year we stayed on the ground and went everywhere. But then in order to discover whether this was the whole story, we rented a helicopter. And we began to understand that this is not chaos but a highly modern system that had been abandoned, then at some point went into reversal, then slowly came out of it.

That has been another interesting discovery: that basically a city [Lagos] could recover from a really deep, deep, deep pit.