teenagers and concerts....when to let go?

I have a 14 year old daughter...barely 14 1/2.

She just asked to go to a concert...in a big city.....with a friend....and I am not chaperoning. 

When did this happen?

Can this happen??

Am I ready for this to happen???

Oh man!  I have been cussing out the dead guy since she asked.  How could he die (yes, he has been gone 14 years but...still...I get all of the hard decisions!) and not be here to make this decision!

It's not that I don't trust her.  Because I do.  It's the world I do NOT trust!

But...this is HUGE! 

Can I implant a tracking device without her knowing?

Can I hire a professional stalker to be there the whole time and keep an eye out on her?

OK...where is the owner & developer of the mini electronic mosquito/spy drone?  Can I borrow it?

When is the time to let this happen?

I want the glass box.  I really want that glass box my sister-in-law talked about many, many moon ago.

To protect her...keep anything from happening to her.  Safe and sound.