Porter Hotel Building, 1898
This Coca-Cola ad is actually a series of three signs. The center panel on the back of the old Porter Hotel reads "Coca-Cola" while the left panel reads, "Delicious and Refreshing." The right side "Relieves Fatigue" panel is very hard to see from the street. The "Delicious and Refreshing" campaign dates to about 1904.
This is best seen from SW Ash between 2nd and 3rd Avenues.