Class Exercise 3: Photomontage Artist

We discovered Mattijn http://www.mattijn.com/mattijnphotomontage.htm and he has pretty cool surrealistic, fantasy images, some of which are urban, some alien and some medieval/past/future. I like the fact that they are surreal, and have the artistic painting/illustration look. I wonder how did he do it, in photoshop or otherwise. I also like how he played with the distortion in perspective in some of the photos.