▁designated ▁a ▁National ▁Historic ▁Land mark ▁in ▁ 1 9 9 7 . ▁ ▁Once ▁the ▁man or ▁house ▁and ▁center pie ce ▁of ▁a ▁ ▁plant ation , ▁R ivers dale ▁was ▁built ▁for ▁Belg ian ▁é migr é ▁Henri ▁Joseph ▁St ier , ▁Baron ▁de ▁St ier , ▁who ▁lived ▁in ▁the ▁Br ice ▁House ▁in ▁Ann apolis , ▁Maryland ▁immediately ▁prior ▁to ▁building ▁R ivers dale . ▁St ier ▁planned ▁the ▁house ▁in ▁ 1 8 0 1 ▁to ▁res emble ▁his ▁Belg ian ▁residence , ▁the ▁Ch ate au ▁du ▁M ick . ▁ ▁Four ▁years ▁later , ▁St ier ▁returned ▁to ▁Belg ium , ▁leaving ▁the ▁un fin ished ▁R ivers dale ▁to ▁be ▁completed ▁by ▁his ▁daughter , ▁Ros al ie ▁St ier ▁Cal vert ▁and ▁her ▁husband ▁George . ▁ ▁The ▁number ▁of ▁slaves ▁employed ▁at ▁R ivers dale ▁varied ▁from ▁around ▁fifteen ▁in ▁ 1 8 0 0 ▁to ▁thirty - two , ▁as ▁reported ▁in ▁the ▁ 1 8 0 6 ▁tax ▁assess ment . ▁ ▁Family ▁life ▁ ▁George ▁and ▁Ros al ie ▁Cal vert ▁were ▁married ▁on ▁June ▁ 1 1 , ▁ 1 7 9 9 . ▁The ▁couple ▁had ▁a ▁large ▁family . ▁Their ▁son ▁Charles ▁Bened ict ▁Cal vert ▁established ▁the ▁Maryland ▁Agricult ural ▁College , ▁now ▁the ▁University ▁of ▁Maryland , ▁College ▁Park , ▁on ▁part ▁of ▁the ▁R ivers dale ▁property . ▁Another ▁son , ▁George ▁Henry ▁Cal vert ▁( J anu ary ▁ 2 , ▁