Bank

Generates cookies from interest.
Overview
The Bank is a building in Cookie Clicker and one of the later midgame structures, notable for being the first building with an initial cost above one million cookies. Like other buildings, it contributes to cookies per second and can be leveled up with sugar lumps after reaching its first level.
A leveled-up Bank is not only useful for increasing production and helping with achievements, but also because higher levels improve its interest rate. This makes it a building with value beyond raw CpS, since upgrading it can increase the return from its banking-related mechanics.
Official description
Generates cookies from interest.