12×12 {-1, +1} matrix of maximal determinant

Ratio of |Det R| to Hadamard bound: 1

M=R^TR=R R^T:

12  0  0  0  0  0  0  0  0  0  0  0
 0 12  0  0  0  0  0  0  0  0  0  0
 0  0 12  0  0  0  0  0  0  0  0  0
 0  0  0 12  0  0  0  0  0  0  0  0
 0  0  0  0 12  0  0  0  0  0  0  0
 0  0  0  0  0 12  0  0  0  0  0  0
 0  0  0  0  0  0 12  0  0  0  0  0
 0  0  0  0  0  0  0 12  0  0  0  0
 0  0  0  0  0  0  0  0 12  0  0  0
 0  0  0  0  0  0  0  0  0 12  0  0
 0  0  0  0  0  0  0  0  0  0 12  0
 0  0  0  0  0  0  0  0  0  0  0 12

R:

++++---+++--
+++-+-+-+-+-
+++--+++---+
+--+--+-----
-+--+--+----
--+--+--+---
-+++------++
+-+-+----+-+
++---+---++-
+------++-++
-+----+-++-+
--+---++-++-

Notes:

1. Maximal matrix first reported by Hadamard [Had].
2. Hadamard matrix.
3. Proved to be unique up to equivalence by Todd [T].