  We present a model-independent anatomy of the $\Delta F=2$ transitions
$K^0-\bar K^0$, $B_{s,d}-\bar B_{s,d}$ and $D^0-\bar D^0$ in the context of the
Standard Model Effective Field Theory (SMEFT). We present two master formulae
for the mixing amplitude $\big[M_{12} \big]_\text{BSM}$. One in terms of the
Wilson coefficients (WCs) of the Low-Energy Effective Theory (LEFT) operators
evaluated at the electroweak scale $\mu_\text{ew}$ and one in terms of the WCs
of the SMEFT operators evaluated at the BSM scale $\Lambda$. The coefficients
$P_a^{ij}$ entering these formulae contain all the information below the scales
$\mu_\text{ew}$ and $\Lambda$, respectively. Renormalization group effects from
the top-quark Yukawa coupling play the most important role. The collection of
the individual contributions of the SMEFT operators to
$\big[M_{12}\big]_\text{BSM}$ can be considered as the SMEFT ATLAS of $\Delta
F=2$ transitions and constitutes a travel guide to such transitions far beyond
the scales explored by the LHC. We emphasize that this ATLAS depends on whether
the down-basis or the up-basis for SMEFT operators is considered. We illustrate
this technology with tree-level exchanges of heavy gauge bosons ($Z^\prime$,
$G^\prime$) and corresponding heavy scalars.
