NOTE Jan 29, 2021: Thanks to a message from BMW X1 I have learned that the building shown in image #3 has undergone a complete face-lift. The numbers for HJK are 640.
The posted coordinates are for the intersection of two highly frequented thoroughfares in downtown Ottawa. The five attached photos are of buildings along a somewhat less frequented thoroughfare, also in downtown Ottawa. Their street numbers have been converted to letters.
Photo #1 ABC = _ _ _
Photo #2 DEF = _ _ _
Photo #3 HJK = 6 4 0
Photo #4 LMN = _ _ _
Photo #5 PQR = _ _ _
The cache is near an historic location, and is located at N45 2Q.[A+H][E+M][P-R] W75 4F.KJM.
When hidden it contained a log, caching manifesto and first-to-find booty. Bring your own writing instrument.
You can check your answers for this puzzle on GeoChecker.com.