Abstract: Aspects of the invention relate to concrete structures having concrete columns. Cables can provides support as a flat beam in the horizontal slab above so that the columns can be used and largely spanned apart. The columns can be substantially aligned in a row or at least one column can be offset from the row of columns. Further, the concrete structure can include large cantilevered surfaces, such as balconies or walkways. Aspects of the invention further relate to a system for forming concrete columns using tunnel forms. In addition, embodiments of the invention can be used to form an offset column in a secondary pour. Aspects of the invention are particularly well suited for creating multi-level buildings of at least five stories.