This is a photo of an exhibit hall at the 1909 World's Fair held in Seattle, the Alaska Yukon Pacific Exposition. It appears to have been taken before the fair opened, when only Frank Nowell was allowed to take photographs on the grounds. It is likely that Otto licensed the image from him.
Note the spelling of "Machinery." Otto was writing captions backwards on the glass negatives, and sometimes misspelled words.
This image is courtesy of Dan Kerlee.
There are three other images numbered 3:
Reuse of image numbers and different image series make it difficult to know how many images Otto published.