This is an exercise for urban areas I learned from artist Peter McCaughey.
Get a map of your local area. The more detailed the map is the better, a print from google earth is perfect.
Draw a circle on the map. You can choose the size of the circle according to how long you want to spend with the exercise, but the line of the circle should cut through at least 6 buildings.
Your goal is to walk the line of the circle as precisely as you can. You want to cover as much of the line as possible, so you might need to approach it from different angles and through different access points and openings.
Your actual journey will be much longer than the line itself. This means ringing doorbells, negotiating entry to buildings, climbing through windows and over fences.
Use your map, and the line on it, to convince people to grant you access. Trace your journey on the map and make notes about how you managed to pass through obstacles.
This exercise was contributed by Pilvi Takala (http://www.pilvitakala.com).