It is well-known that monoids are algebras for the free monoid monad, and can be seen as well as algebras for the associative operad.
Less known is the categorified statement: for example, monoidal categories are 2-algebras for a 2-monad.
Can someone point me to a place (book, paper, web page) where this is constructed in detail? I understand the idea of the construction, but I would like to see it explicitly.
In section 4 of "A 2-Categories Companion" by Lack, it is described explicitly (although briefly). https://arxiv.org/pdf/math/0702535.pdf
Do you know what he means by "the usual free monoid construction"?