I happen to have glasscages pulled up right now researching a purchase...
A glass 673 gal... 12" Long, 36" deep, 36" tall is $9,050
That's the basic box. Add more for low iron glass, lids, drilled, etc, etc as desired.
They don't list any glass aquariums over 36" tall.
Estimated empty aquarium weight 1,210 lbs. Good luck...
In acrylic they stop listing them at 96"
449 gallons, 96" long x 30" deep x 36" tall, is the largest the list at $14,612
again, customizations go up from there.
As always, once in place, I think glass is better. But getting a glass box that big in place may prove so impractical it's not an option.