  Magic-angle twisted bilayer graphene (MATBG) exhibits correlated phenomena
such as superconductivity and Mott insulating state related to the weakly
dispersing flat band near the Fermi energy. Beyond its moir\'e period, such
flat band is expected to be sensitive to lattice relaxations. Thus, clarifying
the evolution of the electronic structure with twist angle is critical for
understanding the physics of MATBG. Here, we combine nanospot angle-resolved
photoemission spectroscopy and atomic force microscopy to resolve the fine
electronic structure of the flat band and remote bands, and their evolution
with twist angles from 1.07$^\circ$ to 2.60$^\circ$. Near the magic angle,
dispersion is characterized by a flat band near the Fermi energy with a
strongly reduced bandwidth. Moreover, near 1.07$^\circ$, we observe a spectral
weight transfer between remote bands at higher binding energy and extract the
modulated interlayer spacing near the magic angle. Our work provides direct
spectroscopic information on flat band physics and highlights the role of
lattice relaxations.
