Written 露地 or 露路 (dew ground) today; used to be written 路地 (walking path).
露地 separates the mundane world and the world of tea (CQ26)
The original purpose was to have a place for the 蹲（つくばい）, because in the old days tea rooms where connected to the house and guests would enter from there.
Make Up
Separated in the inner and outer 露地
The 蹲踞（つくばい）is in the inner 路地, and filled in front of the guests.
60% of stepping stones should be for walking, 40% for viewing (利休, CQ26). However, stones and garden in general should not be too pretty, lest they attract too much attention.
Story of Kuwayama Sakon, whose guest applauded his placement of stepping stones, who then rearranged them because he felt they attracted too much attention (CQ26)
利休:
Fallen red oak leaves
Covering the lonely
Path to a temple
Deep in the mountains
小堀遠州（こぼり えんしゅう）said:
Eine Gruppe Sommerbäume
Ein Streifen Meer
Ein blasser Abendmond
It probably makes sense to have some citrus, so you can tell when it's time for 炉開き.