The wall should be ten Hand-Breadths high: Eruvin 4b, 15b, 86a; Succah 4a; Gittin 15b
Defining the requisite height of a wall as a law told to Moses at Sinai: Eruvin 4b, 15b; Succah 4a-6b
Indoor Walls which don't reach the ceiling: Eruvin 72a-b, 79a-b
For an entity to be part of a wall, one must decide to leave it there: Shabbat 99b
"Combination" Walls
For the height of a wall to include an area which is the wall of a pit, as well as above ground: Shabbat 99a-b; Eruvin 78a, 93a-b, 99b; Gittin 15b
"Imaginary" Walls
Using horizontal ropes, with small gaps in between them: Eruvin 16b
Using vertical reeds, with small gaps in between them: Eruvin 15a, 16b, 19b
Considering a stone as though it were hollowed out, such that it becomes like a corner enclosure for a well: Eruvin 19b
Making a hole in a broad beam which overhangs water, and considering the sides of the beam as walls descending to the water, to permit a person to draw water through that hole: Eruvin 86b-87a
Imagining that part of a wall is hollowed out [Chokikin leHashlim] so that the empty space it surrounds will be large enough to reach a given size: Shabbat 100a; Eruvin 11b, 33b, 101b
Invoking the principle of "Pi Tikrah" to extend an imaginary wall downward from the edge of a roof: Eruvin 25a-b, 90a, 94b-95a; Succah 18b-19a
Using the principle of "Pi Tikrah" to extend an imaginary wall downward from the edge of a roof, to create one or more walls for a house, if the walls collapse on Shabbat: Eruvin 94b-95a
Using the principle of "Pi Tikrah" for walls which meet at a corner: Eruvin 94b
Less-Obvious Types of Walls
A mattress thrown into a pit, dividing the pit as it lands: Shabbat 100a
The sages' leniencies in dealing with walls over water: Eruvin 86a-86b, 86b-87a
Walls dangling in/over water: Shabbat 100b, 101a-b; Eruvin 12a, 16b, 47b-8a, 86a-b
Walls dangling over land: Shabbat 101a-b; Eruvin 12a, 16b, 48a, 86b
Using walls created accidentally/intentionally on Shabbat, for lenient/stringent purposes: Shabbat 101b; Eruvin 20a, 25a
Considering a gradual rise in the ground [Teil haMitlaket] to be a valid enclosure for a well: Eruvin 19b
A wall made up of human beings, who are [not] aware they are being used for this purpose: Eruvin 43b-44b
Wall Problems
A wall which is constructed on Shabbat: Eruvin 43b-44b
The maximum allowable gap in a wall: Eruvin 15b; Succah 15a
The allowable distance between the base of a wall and the ground [Gediyyim Bokin Bah]: Eruvin 14a, 14b
The size of the cubit used in measuring a gap in a wall: Eruvin 3b
Validity of a wall which is constructed atop an invalid wall: Eruvin 24b, 25a
A wall which is built for a temporary purpose: Eruvin 26a
A wall which is built to keep some entity inside a certain area: Eruvin 26a
The walls of a boat, which are technically designed only to keep water off of the boat: Eruvin 90b
