Introduction -- Entryway passages : demystifying dimensions -- Restricted passages : rolled-up extra dimensions -- Exclusive passages : branes, braneworlds, and the bulk -- Approaches to theoretical physics -- Relativity : the evolution of Einstein's gravity -- Quantum mechanics : principled uncertainty, the principal uncertainties, and the uncertainty principle -- The standard model of particle physics : matter's most basic known structure -- Experimental interlude : verifying the standard model -- Symmetry : the essential organizing principle -- The origin of elementary particle masses : spontaneous symmetry breaking and the Higgs mechanism -- Scaling and grand unification : relating interactions at different lengths and energies -- The hierarchy problem : the only effective trickle-down theory -- Supersymmetry : a leap beyond the standard model -- Allegro (ma non troppo) passage for strings -- Supporting passages : brane development -- Bustling passages : braneworlds -- Sparsely populated passages : multiverses and sequestering -- Leaky passages : fingerprints of extra dimensions -- Voluminous passages : large extra dimensions -- Warped passage : a solution to the hierarchy problem -- The warped annotated "Alice" -- Profound passage : an infinite extra dimension -- A reflective and expansive passage -- Extra dimensions : are you in or out? .