The city of Tortage:
Tortage is a match-patch of differently sized houses, city walls and interesting structures. The houses seem almost designed for free running, with many rooves being connected to one another by small crawlspaces, balconies and interconnecting wooden beams. Footholds here are plenty, from tiny window frames to pieces of wood sticking out of the rooves. Tortage is built on fairly flat terrain and so its buildings are of a roughly uniform height. Once you've reached one rooftop, the rest are a trivial matter to get to. The method I used to reach the rooftops involves a series of small careful hops onto a signpost followed by a long running jump onto a roof of around the same height. There are possibly other ways to reach the rooftops of Tortage but after finding one way up, others are mostly redundant.
Running in Age of Conan is more like in a first person shooter than an MMO. Rather than activating a speed buff ability, running is controlled in real-time by holding the shift key. This has the big advantage of letting players make running jumps quickly instead of having to stop and prepare all of their speed enhancements for important long-distance leaps. One thing Age of Conan's control method unfortunately doesn't do very well is a short hop from a standstill. Hopping up onto a small wall isn't impossible but it will require very careful placement and execution. My advice here is to play around with the controls and practice, after a short time the controls will start to feel more natural.
Although running provides a significant increase in speed, there is currently not much else you can do to increase your speed. Gear that increases movement speed exists and a Run Speed skill supposedly increases your speed further by 1% per 100 points invested but neither provide significant enough bonuses. Even with a high level character using speed gear and maximum Run Speed skill, your run speed will reportedly only be up to 14% faster. There are no races or classes with speed abilities and although mounts exist, they may not be any use at all for rooftop exploration.
The city of Khemi:
Khemi, the capitol city of Stygia, is desert town with simple flat-roofed buildings by the river Styx. The main way I found to reach the rooftops relies on a tricky running jump from standstill at a the corner of the wall geometry. Once mastered, a second more difficult jump is required to reach the dizzying heights of the rooftops. Since the height of buildings varies wildly here and buildings are spread apart in clumps, it may not be possible to reach many other rooftops once you're on one. This makes finding additional routes to reach other parts of the city skyline in Khemi a worthwhile goal.