Abstract: A toy building set, including a set of building blocks, in at least some of the sides of which there are slots parallel to the sides, in which there is a locking recess and a connector series, including a set of connectors intended to join the building blocks to each other, in which there are arms joined to each other and equipped with tips, and which arms can be fitted into a slot of a building block, the tips fitting into the locking recess, to join the building blocks to each other. The locking recess is a locking slot pair arranged on the bottom of the slot, which is arranged to expand the slot in the direction of the side of the building block and the arms of the connectors are arranged to be formed of rigid lugs, at the end of which is the said tip, and a shank connecting the lugs to each other.