Where It All Goes Down
There's no way to Google Maps this setting, because we aren't given a lot of geographical information. But we can draw a few conclusions from what the speaker does mention. First up are the gold-gilded tomb monuments in lines 1-2 that belong to dead rulers. We've also got stone floors, statues, and a lot of masonry. From the sound of it, Sonnet 55 takes place in a rich and elegant city ruled by powerful people who like to celebrate themselves.
But it doesn't remain beautiful for long. The marble crumbles; time smears mold across the floor. Warfare tips over the statues and shatters all the fine buildings, while fire takes care of any stuff that isn't stone. It's a pretty bad scene, and our speaker ups the badness so he can contrast it with his poem's main point: the peaceful, serene preservation of a beloved person, in all his unwrecked beauty.