Here is a photo of my Silvermoon Trade Syndicate roof top table.
I was inspired by the STS moving ilicit goods across the roofs of the city and being intercepted by ninjas
We play it such that if you are going up from one roof to another and the difference is waist height or less no movement penalty, waist to top of head means no running/charging and above head height is impassable (unless you can fly).
You can drop down without penalty except from the two tallest roofs to the lowest centre roof which also prevents running/charging.
If you get pushed off a roof or scaffold onto the grey area below the mob following the fight at ground level will kill you :)
Most minis are ok as the slopes are not excessive but top heavy models (Buzenbo) and very light minis (Taka) have trouble so we use a little bit of blu-tack to keep them in place.