Abstract: A concrete building structure is formed or a concrete unit having a closed trapezoid shape of four interconnected sidewalls. The unit is formed of interconnected pre cast concrete sections or cast-in-place sidewalls. A pair of units may be arranged in an abutting side-by-side pair configuration. A plurality of units may be arranged in various configurations, inner and outer concentric rings and in a multi level tiered arrangement. Hallways are formed between adjacent units and may be covered by a deck.