I'd use a really low poly tube say 12 sided on a 12 part arc then run erode. I might then run divide and smooth too. You have inspired me for a sea cave scene, watch this space

I like the concept, did you erode the tunnel walls they look good but maybe more deflections ?

Sketchup, Skatter & Maxwell Render.

Thanks again for the comments its verging on dark and moody for me too, i was trying to add to the atmosphere. The hieroglyphs are a hi res texture with displacement

Very good Mike i think the best I've seen from you. An image has got to have shadows, I'm not a fan of burn't out interiors. Your image has range and depth of light keep going !

Thanks for the comments guys.

Sketchup & Maxwell Render.

Sketchup & Maxwell Render.

model here: https://www.thingiverse.com/thing:2403164

Thanks for the comments guys. For speed and the rendering calculation i simply used two hand drawn planes that were eroded for variation.

Nice model !

Sketchup+Erode plugin & Maxwell Render.

Thanks for the comments guys. It rendered and cleared overnight. I think having no glass in the windows helped. Mike without shadow there is no light

Great Hall, Maxwell Render

model here by Gordon N. https://3dwarehouse.sketchup.com/model/ec6b6390-92a2-492e-9088-7960ca424d9a/Great-Hall-with-columns

I didn't adjust the geometry or add anything to this scene apart from closing the wall behind the camera.

Very good Majid the contrast and saturation make the first images pop.

Super concept & great mountain scene render. Does it have an interior ?

Good job has that architectural style.

Here you go Majid. Here are 3 versions:

1. F STOP 1.6 focal distance seagull

2. F STOP 1.6 focal distance foreground

3. Pinhole Camera (no DOF)

The original image had an F STOP of 5.6 (focused on seagull)

(i don't normally do requests, i had moved on )

Sketchup. Skatter & Maxwell Render.
asset here: https://www.virtual-lands-3d.com/common-cockle.html

Thanks for the responses people.

Thanks for the comments guys.