Crystallographic studies and refinement of a native multilayered phase (Ba42Ti51Fe20O174), occurring in the BaO–TiO2–Fe2O3 system for a Ba:Ti:Fe composition close to 2:2:1, were undertaken using synchrotron X-ray powder diffraction. In this area of the BaO-TiO2-Fe2O3 phase diagram, numerous ternary compounds were found for extremely close chemical and thermal conditions and multilayered phases were always prepared together with a few adjacent phases. The structure of the multilayered compound (Ba42Ti51Fe20O174: space group C2/m, a=9.9512(2) Å, b=17.2366(4) Å, c=42.5272(2) Å, α=90°, β=94.4949(5)°, γ=90°, V=7272.04 Å3, ρ=5.62 g/cm3, Z=2) has been solved by Rietveld analysis of a multiphase pattern containing two other known phases (Ba12Ti15Fe28O84: space group C2/m, a=9.9792(2) Å, b=17.2883(6) Å, c=19.1714(4) Å, α=90°, β=99.7253(6)°, γ=90°, V=3260.04 Å3, ρ=5.30 g/cm3, Z=2, and c-BaTi0.925Fe0.075O3: space group Pm3m, a=4.00779(1) Å, α=β=γ=90°, V=64.38 Å3, ρ=6.04 g/cm3, Z=1). This multilayered structure adopts a 54-layer close-packed structure built with a (chcchhhhcchhhhcchc)3 (Ba,O) stacking along the c-axis to give rise to a very long (crh=127.19 Å) rhombohedral c-axis. Octahedral sites are occupied by a mixture of Ti4+ and Fe3+ cations and tetrahedral ones by Fe3+ cations.