Shield-Barriers were massive slanting walls that protected cities on the planet of Poderis from the seasonal 200 kilometer-per-hour winds. These walls were around 100 meters in height and very smooth with no windows, doors, or other openings. They could not be climbed without special equipment because of their smooth texture and the extremely steep angle. They were designed to deflect winds over the top of the city, rather than stop them completely. The angle made this possible and made the barriers last much longer.
During the year 9 ABY, Luke Skywalker was trapped on a roof connecting to the shield-barrier on Poderis, trying to escape certain capture.He was trying to find out whether Poderis was a transfer point for the Empire's new clone traffic. Luke used his heightened sensing abilities to see if Imperials were nearby; he detected blank spots in which his powers could not detect anything, which could only mean ysalamiri. He then knew it was a trap and jumped up to the roof, only to find he could not go anywhere.
He fashioned a protective wrapping for his hand out of a torn piece of the left sleeve of his tunic. He then made a groove in the outside of the wall which he stuck his hand into and began his descent by holding the lightsaber in front of him, digging out a slanted path for his hand to follow in. After he went about 100 meters across the wall, he cut a hole in the shield-barrier and went back inside the city.