The Limestone Fire is used to keep your villagers warm and safe from predators; this fulfils a need in order to keep them carefree.
The Limestone Fire takes 3 days to unlock, and 2 days to build. This requires 50 Limestone blocks and a Bronze Hammer.
The Limestone Fire will burn for 4 hours, and requires 12 Elm planks and 2 Flint Shards to light it.
By adding 25 Oil canisters to the fire, the burn time can be extended by 12 hours.