Most
people
outside
____________________
United
States
have
never
heard
of
____________________
Great
Serpent
Mound
in
Adams
County
,
Ohio
.
One
of
____________________
most
mysterious
monuments
in
____________________
America
,
____________________
mound
is
____________________
ancient
Native
American
construction
built
to
look
like
____________________
snake
.
While
there
are
____________________
mounds
built
in
many
parts
of
____________________
Midwest
and
____________________
South
,
not
many
look
like
____________________
animals
.
Researchers
refer
to
this
type
of
mound
as
____________________
"
effigy
mound
"
.
Over
1
,
348
feet
long
,
scientists
agree
it's
____________________
very
impressive
monument
,
but
there
is
____________________
disagreement
over
who
built
____________________
structure
.
Some
people
think
____________________
Adena
people
built
____________________
mound
;
others
think
it
was
____________________
Fort
Ancient
culture
.
