The document discusses the Kalasasaya structure at Tiwanaku and how its stone walls were aligned with astronomical events. Specifically, the west wall stones were aligned to mark the summer solstice, equinox, and winter solstice. However, the current Kalasasaya is an inaccurate modern reconstruction from the 1960s, rather than reflecting the original excavation data. While the Gate of the Sun is thought to mark something significant, the main entrance on the east side actually aligns with the equinox.