What did LEGO bricks look like in the past? How did LEGO bricks look like in the olden days?
Can you also show me the bottom of a LEGO brick from the olden days?
The earliest LEGO bricks were made in 1949, and they had completely empty undersides with vertical notches in two of their sides for attaching windows, doors and decorative cardboard inserts:

Then in 1958 (or 1961, depending on the country) the form known today was adopted, with tubes on the bottom and without notches: