Building J and the Main Plaza, Monte Albán, Oaxaca

From the South Platform at Monte Albán, the Zapotec capital on a leveled mountaintop above the Oaxaca Valley, the Main Plaza runs north to the North Platform. The odd building in the foreground is Building J, shaped like an arrowhead and set at about 45 degrees to everything around it. It is usually dated to the last centuries BCE, and its angle has long been read as astronomical, though a later remeasurement found it points at no prominent star. Neither Maya nor Aztec, Monte Albán was a major city for more than a thousand years.