Taken as part of the Wikimedia Foundation Photo scavenger hunt at the San Francisco Exploratorium on 2015-01-21.
<a href="//commons.wikimedia.org/wiki/User:MModell_(WMF)" title="User:MModell (WMF)">MModell (WMF)</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>