ed ▁off ▁by ▁the ▁bank ▁to ▁the ▁highest ▁bid der , ▁including ▁the ▁player ▁who ▁decl ined ▁to ▁buy . ▁If ▁the ▁property ▁land ed ▁on ▁is ▁already ▁owned ▁and ▁un mort g aged , ▁they ▁must ▁pay ▁the ▁owner ▁a ▁given ▁rent ; ▁the ▁amount ▁depends ▁on ▁whether ▁the ▁property ▁is ▁part ▁of ▁a ▁set ▁or ▁its ▁level ▁of ▁development . ▁ ▁When ▁a ▁player ▁own s ▁all ▁the ▁properties ▁in ▁a ▁color ▁group ▁and ▁none ▁of ▁them ▁are ▁mort g aged , ▁they ▁may ▁develop ▁them ▁during ▁their ▁turn ▁or ▁in ▁between ▁other ▁player ' s ▁turns . ▁Development ▁involves ▁bu ying ▁mini ature ▁houses ▁or ▁hot els ▁from ▁the ▁bank ▁and ▁placing ▁them ▁on ▁the ▁property ▁spaces ; ▁this ▁must ▁be ▁done ▁uniformly ▁across ▁the ▁group . ▁That ▁is , ▁a ▁second ▁house ▁cannot ▁be ▁built ▁on ▁any ▁property ▁within ▁a ▁group ▁until ▁all ▁of ▁them ▁have ▁one ▁house . ▁Once ▁the ▁player ▁own s ▁an ▁entire ▁group , ▁they ▁can ▁collect ▁double ▁rent ▁for ▁any ▁und e velop ed ▁properties ▁within ▁it . ▁Although ▁houses ▁and ▁hot els ▁cannot ▁be ▁built ▁on ▁rail ro ads ▁or ▁util ities , ▁the ▁given ▁rent ▁increases ▁if ▁a ▁player ▁own s ▁more ▁than ▁one ▁of ▁either ▁type . ▁If ▁there ▁is ▁a ▁housing ▁short age ▁( more ▁demand ▁for ▁houses ▁to ▁be ▁built ▁than ▁what ▁remains ▁in ▁the ▁bank ), ▁then ▁a ▁housing ▁au ction ▁is ▁conducted ▁to ▁determine ▁who ▁will ▁get ▁to ▁purchase ▁each ▁house . ▁ ▁Mort g aging ▁Properties