▁that ▁they ▁were ▁built ▁as ▁look outs , ▁and ▁others ▁that ▁they ▁were ▁keeps , ▁or ▁even ▁gran aries . ▁Perhaps ▁it ▁is ▁a ▁combination , ▁although ▁the ▁right ▁position ▁of ▁a ▁watch t ower , ▁on ▁a ▁hill ▁top , ▁is ▁the ▁wrong ▁place ▁for ▁a ▁keep ▁or ▁gran ary ." ▁Ar che olog ists ▁have ▁found ▁images ▁of ▁similar ▁to wers ▁in ▁the ▁ru ins ▁of ▁Q ary at ▁al - F ā w , ▁in ▁the ▁Rub ' ▁al - K h ali ▁or ▁the ▁Em pty ▁Qu arter ▁of ▁Sa udi ▁Arab ia , ▁that ▁date ▁from ▁between ▁the ▁third ▁century ▁B CE ▁to ▁the ▁ 4 th ▁century ▁or ▁our ▁era . ▁" Hom es ▁rose ▁two ▁stories , ▁supported ▁by ▁stone ▁walls ▁nearly ▁two ▁meters ▁( 6 ') ▁thick ▁and ▁bo ast ing ▁such ▁amen ities ▁as ▁water - supp ly ▁systems ▁and ▁second - floor ▁lat r ines . ▁One ▁eye - catch ing ▁m ural ▁faint ly ▁dep ict s ▁a ▁multi - story ▁tower ▁house ▁with ▁figures ▁in ▁the ▁windows : ▁Its ▁design ▁res emb les ▁similar ▁dwell ings ▁today ▁in ▁Y emen ▁and ▁southern ▁Sa udi ▁Arab ia ." ▁" M ost ▁of ▁the ▁q as ab as ▁have ▁a ▁circular ▁plan , ▁although ▁some ▁are ▁square . ▁Sometimes ▁they ▁have ▁a ▁band ▁of ▁quart z ▁stones ▁just ▁below ▁the ▁windows ▁or ▁fr aming ▁the ▁windows - ▁one ▁well ▁preserved ▁examples ▁is ▁at ▁the ▁top ▁of ▁W adi ▁Ain . ▁The ▁remains ▁of