Word / simile for a city in decay or in lawlessness

My friend told me that Kobe is the only city in Japan in which he saw hobos and where there are no rules for walking on the sidewalk. I flippantly asked him whether it was the Sodom or Gomorrah of Japan. (Hyperbole, of course!) But this usage feels wrong.

The MacMillian dictionary connotes these cities with sexual decay, primarily:

Sodom and Gomorrah

/ˌsɑdəm ən ɡəˈmɔrə/ two cities in the Bible that were destroyed by God as punishment for the sexual behavior of the people who lived there. People sometimes say that a place is like Sodom and Gomorrah as a way of saying that they are very shocked by people’s sexual behavior in that place.

Wikipedia:

Sodom and Gomorrah have been used as metaphors for vice and homosexuality viewed as a deviation.

Which makes sense.

But how do we convey a sense of non-sexual decay or lawlessness?

degeneration

the state or process of being or becoming degenerate; decline or deterioration.

(google)

Degeneration is a process of decline. Anything that’s getting worse is going through degeneration.

(n) the state of being degenerate in mental or moral qualities. (vocabulary.com)

When I think of a simile for a city in decay, the two terms that come to mind immediately are "Babylon" and "Sin City."

Babylon noun (chiefly among Rastafarians) a contemptuous or dismissive term for aspects of a society seen as degenerate or oppressive, especially the police. "praise them for bringing a new rectitude to Babylon"; see, Google

Babylon Capital of the Neo-Babylon Empire of the mid-first millennium b.c., Babylon has both a historic role and a theological role in the Bible. Certain themes become associated with it. In the Book of Revelation, these themes culminate in the image of the whore of Babylon. As a result of this biblical imagery, Babylon has transcended its historical significance to become synonymous with sin and pride in Western art and literature.

Centuries after the destruction of the Neo-Babylonian state by Cyrus of Persia, Babylon reappears in a dramatic role in the Book of Revelation, a role marked by numerous references to Old Testament imagery. Pride, idolatry, cruelty, and greed are associated with the city.

The dominant image of Babylon in Revelation is the city's personification of a rich woman, the "mother of prostitutes" (17:5). Babylon is a great city that rules over the earth. see, Bible Study Tools

Sin City is an urban area (a city or part of) that caters to various vices, perhaps the most well known example being the Las Vegas Valley in Nevada, United States. These vices may be legal (depending on area) or illegal activities which are tolerated.

Examples of vices include sex-related services (prostitution, strip clubs, sex shops, etc.), gambling (casinos, betting shops, etc.), or drug use (alcohol, marijuana, etc. consumption), and even excessive organized crime and gang activity. see, Wikpedia

And Maarten, "we'll always have Paris."

I would say chaos, disorder, pandemonium, probably.

Although it refers more to state of lawlessness rather than degeneracy, it might cover what you are trying to express:

the Wild West

It is often applied to situations where things are unstable, uncoordinated and outside the control of any governing authority. Originally the term referred to those parts of the (future) United States, where European settlement had extended beyond the control of the central government.

Examples abound

So you might have said 'Kobe is the Wild West of Japan.'

Though, I find, googling, the usual referant of "the Wild West of Japan" is Hokkaido.