We present a nanofabrication method which combines bottom-up and top-down techniques to realize nanosized curved Fabry–Pérot cavities. These cavities are made of a hexagonal closed packed monolayer of silica particles enclosed between flat and curved metallic mirrors. They exhibit geometric cavity modes such as those found in gold shell colloids. These modes manifest as dips in the reflection spectra which shift as a function of the diameter of the used nanoparticles. An excellent agreement is found between experiment and theory which allows us to properly interpret our data. The work presented here constitutes a further step to the development of curved photonics.