We have a small garden at the back of our new build property, and the builders have put a retaining wall at one side. There is a gap of approx 1 metre between the retaining wall and the neighbour's property, and the alley that is formed is about 2 metres high and 6 metres long. We would like to lower the wall as it is intrusive into what little garden we have, and do something with the alley to make it more aesthetically pleasing but we don't know what - we have a garden designer but he is stuck as well - we have explored trays with succulents but these would be inappropriate so we are looking for ideas to try and make the garden as level as possible - would decking work, or does anyone have any other ideas?