A Riddle

Heard this riddle in a homily so I don't claim it as my own.

What are the only man-made things in Heaven?

Let's see:

There are angels.  Nope.

There are Saints.  Nope.

There is " such a great cloud of witnesses".  (Hebrews 12:1)   Nope.

So, what are the only man-made things in Heaven?

The wounds of Christ. 

For all eternity, we will be able to see the wounds that brought us to our Heavenly home.  Thank you, Jesus.