One set of hollow blocks and two sets of twisted blocks from Plan Toys fit in a medium LL Bean tote, my easy toy clean up solution. There blocks have been a favorite of the 3-5 year old age range both girl and boys. Here my son who just turned 4 is building cities.
He is also a big fan Tegu Blocks to build cities. He often plays with both types of blocks on the floor.
Here is some of what he made today.