bank, hotel, office
wall

open
close, lock
break into, crack

be, feel, seem
become
keep, remain, stay
make sth, render sth
The army experts made the bomb safe.

keep sth
Keep your money safe by carrying it in an inside pocket.

consider sth, declare sth, deem sth
The water was not considered safe to drink.

extremely, fairly, very, etc.
absolutely, completely, entirely, perfectly, quite, totally
a completely safe and secure environment for young children
The woods are never entirely safe for women on their own.

comparatively, reasonably, relatively
enough
You should be safe enough, but don't go too far.

inherently, intrinsically
environmentally
an environmentally safe form of energy

from
They were safe from attack.

with
Your money will be safe with me.

better safe than sorry
play it safe, play safe (BrE)
I decided to play it safe and wore a formal suit.

safe and sound
They returned from their adventure safe and sound.

Safe is used with these nouns:
alternative, arrival, assumption, bet, confines, custody, delivery, disposal, distance, driver, driving, drug, environment, ground, guess, harbour, haven, home, house, investment, journey, landing, level, limit, manner, margin, navigation, neighbourhood, passage, place, practice, prediction, refuge, return, road, route, seat, sex, storage, trip, use, vaccine, water, zone