Le passe-muraille

I'm running out of ideas! Yet another walk round Lézignan in search of blips. I have discovered parts of the town I didn't even know existed. I'd never come across this before; it was on the wall of a house in a back street. No explanation of its significance, so I can't enlighten you with any further information. Instead I'll leave you to figure out the significance of the title. Hint: it's a literary reference.