House wall erected (as replacement) encroaches into neighbors empty lot

My neighbor owns a lot behind property I purchased 14 years ago. He says a city map shows my 16 ft. long rear wall encroaches 1 ft. into his property. He wants me to move the wall or compensate him for loss of value. I have proof the wall was existing before it was replaced, but not sure for how long. Is it protected under adverse possession? What other options do I have?