Related by context. Frequent words. (Click for all words.) 59 Egyptian pyramids 57 solstices 54 burial mounds 54 astronomical observatory 54 archaeological finds 54 archaeologically 53 lava tubes 52 Chaco Canyon 51 landform 51 megaliths 51 landforms 51 stromatolites 50 stupas 50 cairns 50 tombs 50 Mesoamerican 49 archeological 49 archeological sites 49 Ptolemaic 49 archaeological discoveries 49 archeological digs 48 equinoxes 48 microfossils 48 sundials 48 pictographs 48 rock outcrops 48 Mesoamerica 48 archeological excavations 48 geologic 48 archaeological excavations 47 pyramids 47 archaeological 47 planetary nebulae 47 ancient civilizations 47 Stonehenge 47 limestone caves 46 rock outcrop 46 archaeological sites 46 astronomical observations 46 Kuiper belt 46 obelisks 46 megalithic 46 hydrothermal activity 46 excavations 46 classical antiquity 46 royal tombs 46 fossils 46 stone carvings 46 trilobites 46 Tikal 46 hydrothermal vent 46 monuments 46 bas reliefs 46 frescos 45 middens 45 ancient 45 hieroglyphs 45 cosmological 45 microlensing 45 Gliese #g 45 pre Columbian 45 Sassanid 45 Radiocarbon dating 45 Incan 45 Bronze Age 45 ancient relics 45 Palenque 45 medieval fortress 45 petroglyph 45 amphorae 45 flint tools 45 elliptical galaxies 45 petroglyphs 45 intricate carvings 45 Burgess Shale 45 richly decorated 45 Olmec 45 engravings 45 architectural landmarks 45 radiocarbon dating 45 stalagmites 45 Great Pyramid 44 Step Pyramid 44 archaeologists 44 thirteenth century 44 volcanism 44 cliff dwellings 44 relics 44 volcanically active 44 planetary nebula 44 Meridiani 44 geological 44 Type Ia supernovae 44 Etruscans 44 chert 44 cruciform 44 supercontinent 44 archeologists 44 feathered dinosaurs 44 Byzantine era 44 Stupa