How can I get inside the Old Mint?

Hint 1 of 10:

This is a "classic" square puzzle.

Hint 2 of 10:

The object is to have every row and column (top to bottom; left to right; and
diagonal) add up to the same number.

Hint 3 of 10:

This puzzle is a "Mason" square.

Hint 4 of 10:

The number is NOT 13, even though all of the clues mention that number.