A single-crystal-to-single-crystal (SCSC) photodimerization is achieved using Au(I) coordination and aurophilic interactions. The rigid Au-2(dppbz)-(CF3COO)(2) precursor (dppbz = 1,2-bis-(diphenylphosphino)benzene) self-assembles with 1,2-trans-bis(4-pyridyl)ethylene (bpe) to afford a discrete [Au-4(dppbz)(2)(bpe)(2)](4+) macrocycle in the solid state. The alkene undergoes a [2 + 2] photocycloaddition reaction. The photoreaction proceeds via a rare SCSC transformation in quantitative yield that generates [Au-4(dppbz)(2) (4,4'-tpcb)](4+ )(4,4'-tpcb = rctt-tetrakis(4-pyridyl)cyclobutane) stereoselectively. Mechanical strain induced by the photoreaction is evidenced by the formation of ramp features on single-crystal surfaces using scanning electron microscopy.