We present a whirlwind tour of connections between particle production from the quantum vacuum, black hole horizons, and accelerated boundaries. Thermal (blackbody) radiation is particularly interesting, and can arise from an electron moving on a trajectory first discussed by Leonardo da Vinci, which can be mapped to an accelerating but asymptotically static mirror, and then to a Schwarzschild black hole with a horizon modified at the Planck length. A de Sitter horizon is closely connected to cosmic acceleration and we explore some aspects of gravity beyond Einstein.