... or windows. We could call the building housing these green things "greenhouses."
What would be even cleverer is to just plant the crops where the sun falls in the first place, and just do one layer of crops directly in the soil already present in that location. This would obviate the need for the multi-story tower, mirrors, soil transportation, etc. A "non-vertical farm," if you will. I think it could be a real money spinner!
To solve the year round garden problem, it would be better to grow them in enhanced greenhouses. Then could use sunlight when available and LEDs the rest of the time for decrease in costs and increase in efficiency. There would be no improvement in land usage but even big cities have empty land nearby. I sort of think current vertical farming pivoted when original idea didn't work, but there is better way to do the pivot.
These typically increase the growing season and permit crops to be started (e.g., seeding rooms or houses) or harvested before or after what would otherwise be a killing frost. With apparent increases in weather variability these might have increased applicability.
Low-Tech Magazine's Agriculture section includes numerous traditional such technologies.