Here are your options:

1. Check for your metal property pins. Properties are supposed to have a metal pin in the ground at each corner that can be located with a metal detector. They are not always easy to find.
2. Review your property survey.  When you bought your home, it’s likely you received a map, also known as a plat, showing property lines and measurements. If it wasn’t included with your paperwork, check with your county clerk’s or surveyor’s office.
3. Hire a surveyor. *Most reliable option. If you don’t have a survey or plat — or at least not one that’s at all up-to-date or specific — you may choose to hire a professional to do a land survey. The surveyor can measure and map the property and will generally also mark the corners of the property with stakes.

City Hall WILL NOT attempt to locate resident property pins.

 (source: How Do I Know Where My Property Lines Are? (zillow.com)