softyjain, If the windows need to be replaced I recommend looking at fixed steel to maintain the narrow profile of the windows and small window lites. Using fixed instead of operating will be a cost savings if you don't need to open them. Another option for hanging from the ceiling is a decorative light or chandelier. That way you still have light into your ceiling at night. We offer Renaissance solid bronze windows that don't require any finish or finish maintenance. Architects designers love the rose bronze color, which closely matches copper gutters. http://www.houzz.com/projects/152134/Renaissance-Solid-Bronze-Windows---Doors-by-Progressive-Solutions You may also be interested in this ideabook- http://www.houzz.com/ideabooks/18543834/thumbs/Bronze--Copper---Steel-Window-Ideas

Sounds to me like you might need an architect. DIY design sounds like a bad idea in this case. If I was an owner I would want a pro involved.

sararahim123 What constitutes an adequate illumination level varies from person to person. What exactly do you require illuminated? If its simply ambient light you would have tiny lights as shown that throw light on the stairs itself. If a bit more is required you could consider adding a railing with a light under. If general illumination is what you are going after, but in a muted way, would suggest wall scones that throw light upwards onto the ceiling, diffusing the light.

Concrete gives more premium look i feel if i consider it for a long span of time... Steel will cost alot and plus it will require maintenance. Any guesses how can cost effective moulds can be created of such shape if we wana do it with concrete?