I am establishing an 'out' apiary in central Oxford. I already maintain a single hive at home.
This will consist of 2 hives with Commercial brood bodies. They are sited on the roof of a building, equivalent to the 5th floor. I will be populating them with swarms caught in the local area. They have loads of forage in University Parks, down the Cherwell river and in nearby college gardens.
I've read that bees have no problem being site high up, if the placement is not too exposed. It will be cold and windy during the winter so I'll have to consider how to mitigate this as the season draws on.