▁of ▁the ▁cable ▁car ▁structures ▁and ▁the ▁demol ition ▁of ▁the ▁cable ▁car ▁after ▁three ▁years . ▁ ▁Cast les ▁ ▁With ▁a ▁few ▁exceptions , ▁the ▁cast les ▁in ▁the ▁Middle ▁Rh ine ▁Valley ▁were ▁constructed ▁between ▁the ▁ 1 2 th ▁century ▁and ▁the ▁first ▁half ▁of ▁the ▁ 1 4 th ▁century . ▁They ▁were ▁usually ▁built ▁on ▁the ▁middle ▁terra ces ▁that ▁were ▁created ▁during ▁the ▁formation ▁of ▁the ▁valley . ▁ ▁In ▁the ▁ 1 0 th ▁and ▁ 1 1 th ▁century , ▁castle ▁building ▁had ▁been ▁a ▁privile ge ▁of ▁the ▁king ▁and ▁high ▁nob ility . ▁ ▁Struct ures ▁from ▁this ▁period ▁were ▁usually ▁made ▁of ▁wood ▁or ▁ram med ▁earth ▁and ▁have ▁not ▁surv ived . ▁ ▁The ▁weak ening ▁of ▁imperial ▁power ▁began ▁in ▁the ▁ 1 2 th ▁century ▁and ▁the ▁power ▁of ▁the ▁Prin ces ▁grew . ▁ ▁Between ▁ 1 2 2 0 ▁and ▁ 1 2 3 1 , ▁several ▁important ▁rights ▁( reg alia ) ▁were ▁transferred ▁to ▁the ▁spiritual ▁( Con fo eder atio ▁cum ▁princip ibus ▁ecc les i astic is ) ▁and ▁temporal ▁( Stat ut um ▁in ▁fav orem ▁princip um ) ▁princes ▁of ▁the ▁emp ire . ▁ ▁From ▁ 1 2 7 3 , ▁the ▁Emperor ▁was ▁elected ▁by ▁the ▁Elect ors ; ▁in ▁ 1 3 5 6 ▁imperial ▁f ief s ▁became ▁territorial ▁states . ▁ ▁This ▁was ▁also ▁the ▁period ▁when ▁most ▁cast les ▁were ▁constructed . ▁Four ▁of