Sun, Moon and Earth by Robin Heath is a short introduction to understanding the relation between the three celestial bodies in the title. The astronomy and geometry are written for a layman's level, without being too dry or technical, but not childish either. Heath details how the earth moves about the sun, with seasons and the calendar, as well as two types of lunar cycles, equinoxes, solstices, eclipses, etc. The book details how our calendar works and offers some interesting alternatives. There's even a short chapter about Stonehenge, which can be further explored in another volume by the same publisher.
I found it fascinating how much megalithic astronomers knew about the sun and moon cycles, especially the geometry, but then again, they didn't have much else to do and light pollution was almost non-existent then. Imagine what the sky looked like in 3000 BC! The book is full of cool illustrations and tables and overall is well put together.