An Activity License is required for all businesses and non-profits operating in Philadelphia. Complete this form for any facility within your responsibility for which there is a private business use.You need a Rental License to rent housing units or properties to tenants. Sidewalks, alleys, driveways, and retaining walls are private property. They belong to the property owner. Pennsylvania law doesn't establish requirements as to the size, design and content of the no trespassing sign. My colleague's answer is correct in general, you don't have the right to enter private property if the owner does not want you there. A person may also trespass when they have permission to enter the property, but then refuse to leave when the owner asks. You can obtain a CAL for free. To get a CAL, you must fill out a license request form.