single word to describe futuristic and modern building

Solution 1:

Because architectural theorists/historians have defined modernism and futurism (and many derivations of these terms) to the past, I would be careful in using such terms. Two words that would generally avoid specific period definitions would be contemporary and progressive.

You could go with Post-Contemporary but that may be too esoteric.

Lastly — and this has nothing to do with your question — if the structure is made of the same stuff as the Sydney Opera House, please refer to it as concrete, not cement.

Solution 2:

Neo-futurism was coined as an early 21st century (that's now) movement that covers architecture, arts and design. I would suggest neo-futuristic is the appropriate adjective.

Solution 3:

A futuristic and modern building might be called a futurama.

futurama: (noun) an exhibition or display that attempts to depict certain aspects or elements of life in the future.

-rama noun suffix meaning "sight, view, spectacular display or instance of," 1824, abstracted from panorama (q.v.), ultimately from Greek horama "sight, spectacle, that which is seen."

Solution 4:

I have always liked the expression 'cutting-edge architecture'