Superhydrophilic and superhydrophobic surfaces were studied with an eye to industrial applications and use as research tools. Conventional methods involve complex and time-consuming processes and cannot feasibly produce large-area three-dimensional surfaces. Here, we report robust and large-area alumina nanowire structures with superhydrophobic or superhydrophilic properties, generated by an inexpensive single-step anodization process that can routinely create arbitrary three-dimensional shapes. This process is expected to open up diverse applications.