Agapanthus are everywhere in Menton at the moment. In the photo below you see them in the beautiful gardens of the Serre de la Madone. The close-ups - and going to seed - are in my garden in Gorbio.
This is a South African plant that is more than happy in the south of France. It's a member of the lily family, hence the common name of African Lily or Lily of the Nile.