The original Dungeons & Dragons boxed set was the first published role-playing game, a fantasy game system modeled on medieval Europe. This set introduced elements which would become standard in later editions, including abilities (such as strength, intelligence, and dexterity); character classes (fighting-man, magic-user, cleric) and character levels; races (human, dwarf, elf, halfling); armor class; monsters and treasure; underground dungeons consisting of halls, rooms, and doors protected by tricks and traps; and magic items, such as intelligent swords. The set also presents rules for travelling through the wilderness by land and sea, hiring specialists as well as men-at-arms, constructing fortifications and establishing baronies. The set defines movement rates and areas are using inches, like that of the miniatures rules from which the system descended.