Integrated circuitry comprising a memory array comprises strings of memory cells comprising laterally-spaced memory blocks individually comprising a first vertical stack comprising alternating insulative tiers and conductive tiers above a conductor tier. Strings of memory cells comprise channel-material strings that extend through the insulative tiers and the conductive tiers. The channel-material strings directly electrically couple with conductor material of the conductor tier. The conductive tiers individually comprise a horizontally-elongated conductive line. A second vertical stack is aside the first vertical stack. The second vertical stack comprises an upper portion and a lower portion. The upper portion comprises vertically-alternating first insulating tiers and second insulating tiers that are of different insulative compositions relative one another. The lower portion comprises a horizontal line above the conductor tier that runs parallel with the laterally-spaced memory blocks in the first vertical stack. Other embodiments, including method, are disclosed.