Trilateration is the technique of determining absolute locations of points using distances and the geometry of circles and spheres. We study the problem of placing distance-measuring guards (towers) in a simple polygon in order to locate points in the interior. We show that in any polygonal art gallery of \(n\) sides it is possible to place \(\lfloor \frac{2n}{3} \rfloor\) towers so that every interior point of the gallery can be trilaterated/located without ambiguities. This improves the previous best upper bound of \(\frac{8n}{9}\) by M. Dippel and R. Sundaram presented at CCCG 2015. We also show that in some cases \(\lfloor \frac{2n}{3} \rfloor\) towers are necessary.