There are many cypress in the alien city, I was right (Ridley is very familiar with tree symbolism). A bit of symbolism here and there. Like the overall look of the city (the shrine looks great), especially from this top perspective. I always expected that David will turn to be some kind of pseudo archvillain or better yet anti-hero of these movies. Only that is enought to keep me hyped, not to speak about everything else this movie has in store for us. Its obvious this kind of SF movies are not for all (even not for all Alien fans). I can now say with great certainty that Covenant is going to be one of my favourite alien related movies. Why are cypress important, well all things point that this city is the only inhabited place on the planet, why... well because its a sacred place, a sacred planet if you will. I think those pseudo engineer humanoids are some kind of priests.