I tried the Precambrian Era Time Portal yesterday.
Feels like a great place to retreat, at least energetically.
It feels very peaceful and isolated there.
https://forum.enlightenedstates.com/t/precambrian-era-time-portal/61489
Alternatively you can try the Portal to Mars.
I am suggesting these portals to other eras and planets because I don’t think there are any places on physical Earth, and especially with human made temples or monasterys, where one can find peace from human stuff and similar energies. Earth is a low vibe planet in general, regardless of where you go, at least in our geological Era (my personal opinion).
Therefore, I would straight up look for other planets and higher astral realms (like Vaikuntha Loka for example) where finding peace is much more likely and thus better for contemplation.