We consider the general Three-Higgs Doublet Model (3HDM) and identify all limits that lead to exact SM alignment. After discussing underlying symmetries can naturally enforce such an alignment, we focus on most economic setting, called here Maximally Symmetric (MS-3HDM). The potential of MS-3HDM obeys $\mathrm{Sp(6)}$ symmetry, softly broken by bilinear masses explicitly hypercharge Yukawa coup...