Emilia, this book is enormous. Why so massive?

Well, we took the idea of the atlas from the Times Atlas of the World. We wanted to have big pages so that we'd have one project per page so as to illustrate and create a good narrative around a project without having to flip the page. We want the reader to really understand the project with one glance. With a normal-size book you'd need two or three pages to convey the building. Plus, we like the idea of putting two different projects on one spread. They may be close to each other geographically, but could be completely different.

How much does the book weigh?

Eight kilos. I don't know what that is in pounds.

That's over 17 pounds. How is one supposed to hold a really long, wide, 17-pound book?

How do you usually read?

With a book on my lap, or holding it. How do you read?

I sometimes put books on the floor or a desk. Maybe a coffee table. This book is large, but it's not too dense. It's a real pleasure to go through.

I find that I return to geographical atlases over and over again because there's always some new detail to learn. Sure I know where Poland and France are, but in looking through an atlas I remind myself which river runs through Moscow, or I see precisely where some minor city is located.

Yes! That's part of why we organized this book like an atlas. By organizing things in a geographical sequence you have a project you know well, a masterpiece, and then next to it you have a nice surprise. There is continuous discovery with this book, which keeps you coming back. And it's the same for the images that we selected. We searched through lots of archival images to find pictures from the time the structures were built. We tried to capture the time in which the architect actually worked by showing pictures that depict the building at the time it was completed.

In an atlas, though, you might have equal space dedicated to each section of the globe. But in a trek through 20th-century architecture you're bound to spend more time in Europe and the USA than necessarily in Africa or Australia. How did you distribute the space given to each continent in the book?

Well, the idea of an atlas is that it looks at every corner of the world, and yes, most books about 20th-century architecture mainly focus on Europe and the USA with perhaps some in Japan and Latin America after the second World War. So we had to change our measure of quality from country to country. Sometimes in Africa the projects, on the whole, are less strong than those in, say, Switzerland. But within each country we're showing off the most important and best buildings. There are also countries which, in the 20th century, have gone through cycles of quality. In Russia, during the revolution and in the 20s and 30s you've got a lot of masterpieces. Then the period from the 70s to the 80s is not very interesting and finally toward the end of the century it picks up again. If we only showed the very best buildings of the 20th century then it would be a book with every Corbusier building.

And that book already exists several times over.

Yes. So a geographical approach is a fresh take on 20th-century architecture. For me, the best discoveries came in the countries I was less familiar with. The development of architecture in North Africa, in the early part of the century, was clearly greatly influenced by colonizing countries. And it's pretty incredible how those architects imported forms from Europe without much thought for how appropriate they are to their new locations. And then, as a new generation of local architects comes up they become far more aware of local materials and the local climate. You get a really interesting translation of the modernist movement into a great variety of regional movements.

In addition to being informative and eye-opening, this book is also really pretty. Were you conscious of trying to make a really beautiful reference book? It's not a genre of literature that tends to be very attractive.

In general, the design of a book is really important in relation to its content. We don't have in-house designers at Phaidon so whenever we do a book we try to understand which designer can really interpret our vision. In this case, we needed someone who could create a good narrative page-by-page. Then the designer had to combine our text—which is really accessible, no jargon—with the imagery to create real pleasure when looking at the page.