2618. Why would you always be able to find these characters? 後 宿 邸 宇 堤

They represent things found on a map or used to navigate.  

後  GO, ato, nochi - after

宿  SHUKU, yado - lodging, shelter, pregnant

邸  TEI - mansion, residence

宇  U - heaven

堤  TEI, tsutsumi - bank, embankment, dike