The 7th level spell Teleport (PHB p.281), it:
instantly transports you and up to eight willing creatures of your choice that you can see within range, or a single object that you can see within range, to a destination you select.
The destination you choose must be known to you, and it must be on the same plane of existence as you. Your familiarity with the destination determines whether you arrive there successfully.
Following this is a table of familiarity against chance of success and descriptions of the terms used. I won't include this here as that would be most of the spell.
Here is a link to the spell in the 5e SRD: Teleport.
There are situations where a creature will cast Teleport to get to a destination they can actually see at the time of casting.
What familiarity does the caster have with the destination if they can see it?