The Roost is one of the newer boulder fields to be discovered and climbed at in southern Illinois. It has, however, received quite a bit of notoriety due to a handful of hard classics that have been established here such as Chuck Norris (V9), Ring of Fire (V10), Eternal Sunshine (V9), Year of the Renegade (V12), Beaver Eater Delux (V8) and The Gobbler (aka Illinois biggest sloper) (V8) amongst others. The rock quality ranges from perfect to mediocre with it usually improving as the grade rises. The Roost is mostly a somewhat broken and usually very steep cliff line that goes on for maybe 150 yards along with a handful of free standing boulders that all sit in quiet woods next to a serene lake. There are maybe 40 or so established problems here with some projects and possibilities for more. I am not including any specifics for problems because I don't have any pictures and when I've been I just climb what looks fun or attempt what I have scene in videos. I encourage you to do the same or better yet buy and reference Matt Bliss's awesome guidebook "Sandstone Warrior" documenting problems at The Roost, Jackson Falls bouldering, Elephant Rocks SP, Giant City SP, The Beach and many more bouldering areas in southern Illinois.
To find The Roost you must first get to Jackson Falls.
To do this head south down I-24 until you can exit onto HWY 45 and head northeast until you reach the town of Ozark. At the Ozark General Store take a right (east) down Ozark Road for approximately 4.5 miles until you make a sharp left curve at Zion Church/Cemetery. Then make a right after a couple hundred yards onto Trigg Tower Road (which is gravel) (please drive slowly down this road as you pass a house and there are many blind spots you could easily smash into another climber coming out - it wouldn't be the first time). After two miles of this you will come upon the main parking area for Jackson Falls. Keep driving past this for another mile or so passing pull offs and many great, free camping spots and the dog walk for Jackson.
After you pass through Jackson the last main camping area is The Pines (please don't park here), across from this is a somewhat open field. Park immediately after this on the right and follow the four wheeler trail into the woods. Follow the trail - it will fork a few times but ends up reconnecting in the end. You will come to a small creek that crosses the trail and a rock cairn. Turn left here and follow it along the creek for a few minutes. The trail will soon start dropping and boulders and the lake will come into view.