COMMON BONDS
'Purpose of the structures seen here: <a href="http://www.j-archive.com/media/1998-02-25_J_25.jpg" target="_blank">[1]</a> <a href="http://www.j-archive.com/media/1998-02-25_J_25a.jpg" target="_blank">[2]</a> <a href="http://www.j-archive.com/media/1998-02-25_J_25b.jpg" target="_blank">[3]</a>'
astronomy (or observatories)