Vintage Cars: starting, mustang 289, selinoid

Question
I have a 68 mustang.  289 engine.  It won't start.  When I turn the key I hear a clicking sound.  I think it's the solenoid, which is mounted inside the engine compartment on the fender near the battery.  

Does this sound like what you think the problem is?  Thanks in advance for your help/advice.

Answer
perhaps, how old is the battery, make sure the connections are good and tight and clean, make sure the ground (-) is in good shape.  A battery can go bad for no real reason.   A clicking may be a bad starter or selinoid or battery or a simple ground issue,  Try tapping the starter with a hammer ( not too hard ) and see if that helps, sometimes the armature hits a dead spot and does nto connect , especially if it is old
My guess is the battery.
Good luck
keep me posted
Ron