1. In the middle of the continents
The oldest rocks on our planet can be found in the middle of the continental masses. Such places are the interior of Australia, from where the oldest rock have actually been found, Siberia, Central Africa, the interior of Canada, the interior of Brazil... The reason why this is the case is because of the subduction that occurs between the plates. The oceanic plates are the ones that subduct, thus their crust is getting destroyed, so their rocks are younger. The continental plates, on the other hand, are not getting subducted, but instead they either collide with other continental plates, or go above the oceanic plates that subduct below them, thus their crust is usually not destroyed, except on the surface part where the weathering and erosion are taking part.
2. at conservative boundaries
The conservative plate boundaries, more commonly referred to as transform plate boundaries, are the ones where the tectonic plates are sliding past each other. Instead of the plates moving toward each other, or away from each other, at these boundaries the plates are moving in sliding past each other while moving in opposite directions. The pressure between the plates on these boundaries results in cracks in the crust, known as faults, and they are parallel to the plate boundary. Also, these boundaries are very active geologically, and they often cause earthquakes to occur in the surrounding area.
