I can't make up my mind what I like better. The black stairs and the encaustic tiles that link the two floors? The artwork, especially the photography? The sleek, black kitchen as counterbalance to the white, bright apartment? The light flooding in from the windows? The view? Perhaps all of it! Whatever it is, it's apparent that I love this penthouse in the Dutch city of Utrecht, home to interior designer Jeroen van Zwetselaar of ZW6.