Male and female protagonists explore giant building with seated statue. Smoke spells out cryptic messages

Question

I am trying to identify the source book of a specific scene which I can't recall well. This was in an American science fiction book sometime probably at least 20 years ago. I remember that a not-very-technological male and female protagonist were exploring (flying somehow?) in a future, post-apocalyptic world, and in their travels they came upon a giant building, which contained a huge seated statue. I remember wondering if the building was meant to represent the Lincoln Memorial. They did not understand what the building was for, and wondered about it. I don't believe they were able to enter it. Also, the building seemed to be emitting smoke into the sky, which somehow spelled out cryptic messages one letter at a time, which could not be understood. They wondered at it a bit and moved on. The overall effect was a bit eerie and mysterious as I recall.

I remember the style of the story having been in the general vein of Philip Jose Farmer's "Dark is the Sun", or perhaps Bryan Aldiss' "Hothouse", but I have looked at both of those and haven't been able to identify the scene. Clifford Simak had some things in a similar style, but I didn't find it there either.

Any ideas?

Answer 1

Possibly The Jewels of Aptor by Samuel Delaney. There is a Wikipedia article on the story here.

The protagonist is Geo and he is travelling with a priestess. The scene with the building is:

The building they suddenly came upon had tongues of moss licking twenty to fifty feet up the loosely mortared stones. A hundred yards from the water, the jungle came right to its edges. The whole edifice had sunk a bit to one side in the boggy soil. It was a far more stolid and primitive structure than the barracks. They scraped and hacked in front of the entrance where two great columns of stone, six feet across at the base, rose fifty feet to a supported arch. The stones of the building were rough and unfinished.

And the statue inside the building:

Behind a twisted metal rail and raised on steps of stone, the ruins of a huge statue sat. Carved from black rock, it represented a man seated cross-legged on a dais. An arm and shoulder had broken off and lay in pieces on the altar steps. The hand, its fingers as thick as Urson's thigh, lay just behind the altar rail. The head was completely missing. Both the hand still on the statue and the one in front of them on the steps looked as though they had once held something, but whatever it was had been removed.

But the protagonists travel by ship not by flying. Also the building doesn't emit smoke, though a few pages earlier we have:

Twigs and rubbish littered the metal floor. They walked between double seats toward a door at the far end. Effaced signs still hung on the walls.
N .. SM .. K .. G

which if you really stretch it might be mysterious letters related to smoke.