The first thing that came to mind 

When reading the word VAULT

Was the inner workings of my heart 

Code to crack 

Difficult to get in

Thick walls 

But nearly indestructible 

My vault of a heart 

Holds all my deepest secrets 

All my memories 

All my pain 

Sometimes it’s 

Stronger than it’s own good 

Barring the storm 

keeping out the insane

This heart of mine 

Can be tricky 

Confusing 

Fickle 

But it loves with the strength 

Of the strongest metal

and once you get in

You are 

Golden 

Word of the day challenge : VAULT