1
zona roja;distrito rojo;barrio rojo
1
red line
2
red-light district (marked by a red line on police maps)
See also:
赤線地帯 (あかせんちたい)
3
non-legal public road (denoted by a red line on cadastral maps; sometimes no longer physically existing)
See also:
法定外公共物 (ほうていがいこうきょうぶつ)