Merging data from two columns

I am trying to merge data from two columns into one cell, with one below the other. For example, I have "1234 Main St" in column "a" and "Box 202" in column "b". I need the end result to be:

1234 Main St
Box 202

in one cell.

Thanks in advance.

Try

=A1&CHAR(10)&B1

Then format the cells and in Alignment Tab choose Wrap text.