2 8 , ▁with ▁thirty ▁comm issions ▁to ▁his ▁name ▁and ▁support ▁from ▁fellow ▁architect s , ▁the ▁state ▁exam ining ▁board ▁presented ▁Ad ler ▁with ▁an ▁honor ary ▁license . ▁ ▁From ▁this ▁point ▁forward , ▁Ad ler ▁operated ▁his ▁practice ▁alone . ▁The ▁Ro aring ▁Tw ent ies ▁was ▁Ad ler ' s ▁most ▁prosper ous ▁time , ▁but ▁he ▁strugg led ▁during ▁the ▁subsequent ▁Great ▁De pression . ▁An ▁injury ▁in ▁ 1 9 3 5 ▁during ▁a ▁fo x ▁h unt ▁further ▁slow ed ▁Ad ler . ▁Also ▁that ▁year , ▁Ad ler ▁met ▁with ▁Jer rod ▁Lo eb l ▁and ▁John ▁A . ▁Hol ab ird , ▁who ▁were ▁commission ed ▁by ▁the ▁Arm our ▁Institute ▁of ▁Technology ▁to ▁find ▁a ▁new ▁head ▁of ▁architecture ▁for ▁the ▁school . ▁Ad ler ▁recommended ▁Ludwig ▁M ies ▁van ▁der ▁Ro he , ▁who ▁was ▁eventually ▁selected ▁for ▁the ▁job . ▁Over ▁his ▁career , ▁Ad ler ▁designed ▁ 4 5 ▁country ▁houses , ▁ 2 7 ▁in ▁the ▁Chicago ▁area . ▁ ▁A ▁number ▁of ▁Ad ler ' s ▁works ▁are ▁listed ▁on ▁the ▁National ▁Register ▁of ▁Historic ▁Places : ▁ ▁Personal ▁life ▁Ad ler ▁married ▁K atherine ▁Keith , ▁an ▁Illinois ▁social ite ▁and ▁writer , ▁in ▁ 1 9 1 6 . ▁In ▁ 1 9 2 5 , ▁he ▁was ▁named ▁a ▁trust ee ▁of ▁the ▁Art ▁Institute ▁of ▁Chicago , ▁a ▁position ▁that ▁he ▁held ▁for ▁the ▁rest ▁of ▁his ▁life . ▁He ▁became ▁a ▁wid