What are some of the most memorable grave/tombs in adventure games? I’ll start it off    

Great choice! I'm from Louisiana and GK1 really captured what the cemeteries look and feel like. That whole game captures the essence of New Orleans really well, even if a few details are off or it exaggerates some things.

Here's one that always stuck in my mind as a good one, for the creepy stillness it gives off by day, and the sense of "I gotta get out of here fast" at night:

   

Great choice! I'm from Louisiana and GK1 really captured what the cemeteries look and feel like. That whole game captures the essence of New Orleans really well, even if a few details are off or it exaggerates some things.

Here's one that always stuck in my mind as a good one, for the creepy stillness it gives off by day, and the sense of "I gotta get out of here fast" at night:

That mandrake root I had to pull gave me nightmares. I also prefer the earlier EGA art

I'm going for a screenshot from a 1980's text adventure called Heroes of Karn. The game had some beautiful 8-bit artwork to accompany the text, including this 'barrow' (which is an ancient hill or mound over a burial site):

   

The graveyard scene in King's Quest IV: The Perils of Rosella is the most haunting to me, but this one is more memorable stylistically.

   

First in my mind appeared grave of Bérenger Saunière.