What about:Very little in the way of fortifications were built during the battle. On day 1, neither side built anything. During that night, troops built lunettes on Cemetary Hill. Morning of Day 2 - continued work on lunettes, fortifications on Culps and mid-Cemetary Ridge. Nothing in the south of the battlefield, with the exception of Chamberlain. Day 3 - no fortifications.
The barriades in front (west) of the Seminary Building
The in-town barricades
Barricades bewteen the Seminary Building and the Cashtown Pike
Earthworks south of the current PA Monument
Vincent's brigade's stone walls (which includes Chamberlain's)
Works on Big Round Top
Breastworks north of Steven's Knoll (could be considered Culp's Hill works)
Works west of the triangular field
Confederate works on Seminary Ridge
These are just the ones I can think of off the top of my head. Some of these were small but I bet there would be a lot if we did more research.