With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
Originally
,
around
1450
,
two
great
fortified
towers
on
both
sides
of
the
river
guarded
a
suspension
bridge
,
which
was
replaced
in
1566
by
a
stone
arch
bridge
.
Originally:O
,:O
around:O
1450:O
,:O
two:O
great:O
fortified:O
towers:O
on:O
both:O
sides:O
of:O
the:O
river:O
guarded:O
a:O
suspension:O
bridge:O
,:O
which:O
was:O
replaced:O
in:O
1566:O
by:O
a:O
stone:O
arch:O
bridge:O
.:O