<p>From the materials for the <a href="https://en.wikipedia.org/wiki/Alaska-Yukon-Pacific_Exposition" class="extiw" title="en:Alaska-Yukon-Pacific Exposition">Alaska-Yukon-Pacific Exposition</a> of 1909, held in Seattle.
</p><p>Alaska-Yukon-Pacific Exposition, Seattle, Washington. In fact, this building ended up as the Manufactures Building; there was no "Horticulture Hall" or "Horticultural Hall" at the Exposition.
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The copyright on the image is dated 1908, so this is presumably before the Exposition. This looks like it is at least retouched and may be a good architectural drawing rather than a photo.
F. H. Nowell. Scanned by the Seattle Public Library.
Edition dated 1909-02-20. Photo copyrighted 1908.
<i>The Argus</i> Alaska-Yukon-Pacific Exposition special issue, p. 14. <a rel="nofollow" class="external autonumber" href="http://cdm200301.cdmhost.com/cdm4/browse.php">[1]</a> (see filename for exact location)