World 7 · Cities Under the Earth, Temples Before Farming · 11 min · PRO
Air underground
The chimney effect and the problem of fresh air
PRO · Ancient Engineering
World 7: Cities Under the Earth, Temples Before Farming is part of PRO
The first world of Ancient Engineering is free. PRO opens the other 24 lessons in 6 worlds — simulations, quizzes and all.
PRO includes
- All 60 labs — every world, every lesson
- Practice exams and certificates
$8.33/mo, billed yearly ($99.99) · or $39.99 monthly