html - push div to left-bottom -

i need div "3" pushed left bottom in second picture. problem is, "1" div larger "3", current setting float: left doesn't work.

i have div contains numbered divs (blue rectangle). code "1" div:

.mainitemphoto {     min-width: 474px;     float: left;     padding-right: 25px; } 

"2":

div.directioninformation {     padding-left: 34px; } 

"3":

.additionalitemphotos {     float: left; } 

"4":

div.aditionalinfo {     float: left;     width: 475px;     font-size: 15px; } 

add "clear" css rule third element:

.additionalitemphotos {     float: left;     clear: both; } 

this push third element below others before in code.