Most ferroelectrics are also ferroelastics (hysteretic stress-strain relationship and response to mechanical stresses). The interactions between ferroelastic twin walls and ferroelectric domain walls are complex and only partly understood, hindering the technological potential of these materials. Here we study via atomic force microscopy the pinning of 180-degree ferroelectric domain walls in lead zirconate titanate (PZT). Our observations satisfy all three categories of ferroelectric-ferroelastic domain interaction proposed by Bornarel, Lajzerowicz, and Legrand.