Depending on how complicated you want to get with this, you can use a basic box projection like an interior mapping shader uses.
See the SimCity 5 example I posted here:
Beyond that you’re getting into slightly more complex raytracing / raymarching setups to get the curved top. See these two examples from ShaderToy:
Basically you’d have to figure out a way to merge those two shaders (a not entirely trivial task) so the top half is an arch, and the bottom is the box.