|Armatocereus or Lemaireocereus cartwrightianus|
Moderate water only during the growing season, otherwise only water if you see wrinkling in the skin. Don't try to soak the whole root ball. Full sun.
A good 'set-it-and-forget-it' plant. The spines stay needle sharp over many years, so set it way over there somewhere.
I know from personal experience that this cactus can tolerate sub-freezing temperatures and snow for at least two days...