▁moved ▁and ▁ere cted ▁in ▁an ▁u pr ight ▁position ▁( columns ▁etc .) ▁ ▁Transport ing ▁was ▁done ▁by ▁land ▁or ▁water ▁( or ▁a ▁combination ▁of ▁both ), ▁in ▁the ▁later ▁case ▁often ▁by ▁special - built ▁ships ▁such ▁as ▁ob el isk ▁carri ers . ▁For ▁lif ting ▁operations , ▁ancient ▁c ran es ▁were ▁employed ▁since ▁ca . ▁ 5 1 5 ▁BC , ▁such ▁as ▁in ▁the ▁construction ▁of ▁Tra jan ' s ▁Column . ▁ ▁It ▁should ▁be ▁str essed ▁that ▁all ▁numbers ▁are ▁estim ations ▁since ▁only ▁in ▁the ▁r ar est ▁cases ▁have ▁mon ol ith s ▁been ▁actually ▁we ighed . ▁R ather , ▁weight ▁is ▁calculated ▁by ▁multip lying ▁volume ▁by ▁density . ▁The ▁main ▁source , ▁J . ▁J . ▁C oul ton , ▁assumes ▁ 2 . 7 5 ▁t / m ³ ▁for ▁mar ble ▁and ▁ 2 . 2 5 ▁t / m ³ ▁for ▁other ▁stone . ▁For ▁an ▁explanation ▁of ▁the ▁large ▁margin ▁of ▁error , ▁which ▁often ▁leads ▁to ▁widely ▁differ ing ▁numbers , ▁see ▁these ▁intro duct ory ▁remarks . ▁ ▁Greek ▁mon ol ith s ▁▁ ▁Below ▁a ▁selection ▁of ▁Greek ▁mon ol ith s ▁sorted ▁by ▁their ▁date . ▁ ▁Roman ▁mon ol ith s ▁ ▁Below ▁a ▁selection ▁of ▁Roman ▁mon ol ith s ▁sorted ▁by ▁their ▁date ; ▁the ▁list ▁also ▁includes ▁work ▁on ▁Greek ▁tem ples ▁which ▁was ▁continued ▁into ▁the ▁Roman ▁era . ▁ ▁Gallery ▁ ▁Greek ▁mon ol