Existing lot type for graveyard. Graveyard gameplay.

I have used lounge, museum and a cafe but all those lots have a building (cathedral or church) so it's not just a graveyard.

Without mods there is a risk of the ghosts getting culled. My solution is to move the most meaningful ghosts in and create a played ghost household with them. It's nice because the ghosts will haunt their tombstones but you can also create a club to gather at your chosen location.

Edit: Not using a lounge, but arts center.