"The vertical city: Rent gradients, spatial structure, and agglomeration economies," co-authored by Stuart Rosenthal, was published in the Journal of Urban Economics. The authors examine the kinds of economic activities that cluster in tall buildings; the types of industries that concentrate on higher floors; the variation in rents in these vertical (as opposed to traditional horizontal) clusters; and the effects of such vertical clustering on city economies. The study is featured in the CityLab article "Cities and the Vertical Economy." 7/19/18