Johnson's pictures of buildings and architecture are large and highly detailed. His cityscapes have so far included Hong Kong, Jerusalem, Zurich, and Liverpool. The last was painted for Liverpool's European City of Culture celebrations in 2008. It took three years to complete, with the artist working alongside up to eleven assistants, and was completed during an artist residency at the Walker Art Gallery. The cityscapes are painted from aerial viewpoints, using models to achieve the correct composition. "Artistic license" is employed to create "ideal" views of the subject cities.