We have been given an image, taken from an apartment building, and a request to locate where the image was taken. To solve the challenge, we need to give the name of a nearby alleyway.
The image depicts a cityscape, including several buildings that could be used to triangulate the location of our apartment building. If the previous challenges were completed before attempting this challenge, they may have realised that the individual being tracked was heading into Melbourne (see (back) On the rails challenge).
The first of the buildings, centred in the image, has a large logo at the top. The logo is difficult to make out but can be read as "ANZ". If you are not Australian, googling "ANZ Australia" will reveal that this is the name of a bank (Australia and New Zealand Banking Group Limited).
Searching up ANZ buildings in Australia will allow us to determine that this picture has been taken in Melbourne, Victoria. The ANZ building is located at 100 Queen St, Melbourne VIC 3000.
The next building is the uniquely shaped white building to the right of the image. From the image, we can see that the building looks to have at least two flattened blue sides and a white corner, unlike the rectangular or square buildings surrounding it. By examining the area around the ANZ building, in Google Maps satellite view, we can locate a similar building at 200 Queen St. Dropping down to street level will allow us to confirm that this is the correct building.
We are now able to confirm a direction from the ANZ building and 200 Queen St. We can also confirm our location further by looking at 200 Queen St, as the white side of the building points in a diagnol direction near the location of the photo.
Either by estimating or by counting the rows of buildings, the photo looks to have been taken one or two blocks away from 200 Queen St.
By navigating street view and examining the surrounding areas from satellite view we should be able to determine that the small street at the bottom left of the image is Hardware St, and the brick building located 112 Hardware St.
With this we can determine that the apartment the image is taken from is at the end of Hardware St, either 318 or 320 Little Lonsdale St.
Now, taking the hint from the challenge description that we are looking for an "alleyway", we can pick the flag as the alley behind our apartment, McLean Alley.
The flag is: DUCTF{mclean_alley}
Note: There are several other points of interest in this image which could be used to locate the apartment building. These include the Westpac building with the red logo, the domed 333 Collins Street, and the buildings surrounding Hardware St.
The photo used in this challenge has been sourced and cropped (to prevent reverse image search) from this real estate listing, image 6 of 11.