If you live in the city (either one), you probably don’t think much about your alley, other than to wish it were wider, and that your neighbor painted his garage. (Although, to be honest, yours peels a bit here and there.)

You might not know the person on the other side of the alley — a bit odd, when you think about it. You’re more likely to know the person on the other side of the street than the person behind you. It’s as if the fact that your backyards face each other is embarrassingly intimate.

The front of your house, that’s the public face. The alleyway is where your pants sag.

If you happen to drive down an alley not your own, you feel like an interloper — and you learn things about the neighborhood.

Stable neighborhoods have uncluttered alleys with garbage and recycling bins standing in formation like soldiers. Challenged neighborhoods have alleys with busted fences revealing unkempt yards heaped with unused plastic children’s furniture, an old tube TV and stout, unidentifiable weeds that grow 5 feet tall.

They could look better. In fact, almost all alleys could look better. But it would take money, laws, initiative and, perhaps most formidable, a change in the way we think about alleys.

If we think about them at all, which we don’t. Which is why they’re ugly.

Old European cities have alleys, but they function more as small streets, arising over the centuries as the cities sprawled without plan.

When American cities were laid out along logical, rational grids, the alleys were designed to hide all the messy, sweaty, smelly stuff. The horses. The garbage. The entrance for servants and tradesmen.

Alleys weren’t pretty, because there wasn’t any reason for them to be pretty.

Horse stalls gave way to barn garages in the early part of the 20th century. Surprisingly, many of the original barns are still around. You might see the original doors from a 1920 garage: pleated, opening side-to-side. The invention of the overhead sliding door in 1921 created an instant status symbol. You can still see some of those early overhead doors today.

But they’re usually not used. That’s because the older the garage, the more it sags. And the more the wood has rotted, the more likely it is that the garage has been sealed up for years. (Makes you wonder what’s in there. Block after block of accidental time capsules, filled to the rafters with boxes of stuff.)

Some urban designers are proposing that we do away with alleys altogether: Knock down the garages, rip out the concrete. Turn alleys into gathering spaces with gardens or maybe small houses (aka accessory dwelling units, or ADUs) for relatives or renters. Instead of a weedy mess of unkempt trees, crumbling retaining walls and pieces of disassembled engines, you could have a shared space with rain gardens and solar panels that knits blocks together.

It’s a nice idea — in the abstract.

Doing it would deprive homeowners of the right to do what they wish with their property, of course.

And rehabbing alleys could also gentrify challenged neighborhoods, which could push out any lower-income residents. One “green alley” would lead to another until the neighborhood would be full of cold press coffee shops and overpriced burger bars.

You suspect there are a few urban planners who would say, with regret, that such a demographic realignment is the price for keeping the core city healthy.

If it happens, it’ll give the city another selling point the suburbs can’t match.

The alley was never part of the suburban vernacular. After World War II, a new style of house put the garage right next to the house in the front. The car was invited to be part of the home, like a pet allowed to sleep inside instead of out in the doghouse.

There aren’t many suburban alleys to reclaim. Future developments in the exurbs might add upscale alleys, landscaped with subtle curves and custom lighting. But it seems the sort of thing that the central cities ought to pioneer.

The idea of a greenway behind your house where people socialize will seem attractive to those who want density and lots of happenstance interaction. A few zoning laws and regulations would do the trick.

Or, you know, people could just clean up their alleys and hang out there with their neighbors now and then.

But it’s hard to persuade anyone to spend the time and energy. Alleys belong to everyone, which means they belong to no one in particular.