The trail head is 2.5 miles north of Utah Route 95 along a BLM gravel road. The road is a north turn just after passing through the engineered notch in the massive sandstone of Comb Ridge. The trail is mostly an ATV trail so the walking is fairly easy. This trail head is also the starting point for a hike to Hotel Rock. Look for the Walnut Knob petroglyph site in the trail head area also.There are many creek crossings but in fall there is not much water to step through. The trail is sandy and meandering much of the way.
Within the first ten minutes of hiking there is the fairly large Arch Canyon Ruins site that has several wall sections still standing and many collapsed rubble pile structures, and several examples of petroglyphs on the sandstone canyon walls. After that site, there are small and inconspicuous sites higher in the canyon walls. I saw four that I'm sure were sites. I saw other possible sites but they were so far up the canyon walls that it was difficult to tell even with binoculars. On this hike I was focused on reaching the two large arches and didn't stop at the ruins small sites. On a later hike to the Hotel Rock side canyon I looked at the ruins more closely.
Further up the canyon there are more rock fins and monument formations. The canyon forest changes gradually from Pinon Pine and Utah Juniper to Ponderosa Pines with occasional Douglas Firs in shady canyon corners.
I looked at this alcove carefully to see if it was an arch or a ruins site but it didn't appear to be either. Binoculars are handy on this hike for scanning the canyon walls.
It took me about 4:00 hours to get to Cathedral Arch, with Angel Arch another few minutes further. The land status changes from BLM to Forest Service just as Cathedral Arch comes into view, and the trail changes from jeep trail to footpath.
The trip back took 3:00 hours for a total hike of 7:10 hours for the 16 mile round trip. I carried four liters of water and finished the last drops when I returned to the trail head on a perfect late October day of blue sky and about 65 F. This is a long hike but there is a lot to see.
The Arch Canyon Ruins appears to be a combination alcove site and mesa top site. There are some wall sections abutting against a sandstone cliff and collapsed rubble piles in front. 
The third structure seems to have the most details left, showing some entryways and examples of the stonework still in place.
The numerous rubble piles make it appear that this was a sizeable village but there isn't much in the rubble to see for the untrained eye. I didn't find any interpretive information on this site, such as number of rooms or kivas.
Besides the geometric designs there are also a few petroglyphs of animal and humanoid figures. Beyond the ruins site the trail extends as an ATV trail for about eight miles before reaching Cathedral and Angel Arches. Along the way there are opportunites to scan the high cliffs for small Ancestral Pueblo sites.