A post sleeve provides a substantially permanent base for supporting a post for a fence or sign, and from which one post can be removed and replaced with another post. The sleeve includes a concrete body that is poured on site, using a sleeve core prepositioned in the post hole, and around which wet concrete is poured. After the concrete is cured, the core is removed, leaving a post sleeve cavity configured to receive a post. The core can be rigid, or can include a flexible shell and stiffener. A preformed post sleeve top can be attached to the sleeve core and positioned therewith in the post hole, to become a permanent part of the post sleeve, once the concrete cures. A drain is attached to the core, and remains in the sleeve when the core is removed, and can be a percolation chamber, or passage extending below the sleeve.