  In two-dimensional (2D) twisted bilayers, the van der Waals (vdW) interlayer
interaction introduces atomic-scale reconstruction at interface by locally
rotating lattice to form strain-field vortex networks in their moir\'e
superlattice. However, direct imaging the tiny local lattice rotation of the
strain-field vortex requires extremely high spatial resolution and is an
outstanding challenge in experiment. Here, a topmost small-period graphene
moir\'e pattern is introduced to magnify sub-Angstrom distortions of the
lattice and tiny local lattice rotation in underlying twisted bilayer graphene
(TBG). The local periods and low-energy van Hove singularities of the topmost
graphene moir\'e patterns are spatially modified by the atomic-scale
reconstruction of the underlying TBG, thus enabling real-space imaging of the
strain-field vortex networks. Our results indicate that structure-reconstructed
vdW systems can provide a unique substrate to spatially engineer supported
two-dimensional materials both in structures and electronic properties.
