The problem is the DIV with the well class, which I think because it takes up the entire length of the string, and then you have 2 span3 inside, taking up more space than well . (not sure I'm clear enough)
However, if you replace your inner row class with a row-fluid and set the two inner DIV classes to span6 , it should display as you want:
<div class="row-fluid"> <div class="span6">55 Fake Street <br />Fake Town <br/>A1B2C3 <br/> </div> <div class="span6">more Info <br />Blah Blah <br/>Blah <br/> <input type="button" class="btn btn-primary" value="Use Location" /> </div> </div>
I played the fiddle here .
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