40. Symmetric Bridgechallenge
Roel Huisman from Portugal made this little symmetric bridge.

Build a bridge with the biggest area with a set of pentominoes.
Notice the rule used to join the 12 pentominoes is that they must touch along the full edge of the square and not just at the corners.
The bridge must have a symmetric inside border.

This will make finding a solution to the above problems easier:
PENTOMINO