When teens have a curfew of 11:30pm where do they go exactly ?

They go to stores that are open late. Restaurants like iHop that used to be open 24/7 were a popular place to go buy coffee or fries, hang out, and talk. Sometimes they go to friend's houses. Here when the kids are old enough to drive, they meet up around town in different parking lots. They roll the windows down and listen to music. Guys pop the hoods on their vehicles and pretend like they're in Fast & the Furious, act like they know what they're talking about. They spend a lot of time trying to be cool, impress each other, flirt, talk, dance, joke, and make memories. Building relationships they may have for a life time. Say goodbye to friends that are graduating and moving away.

Also some kids have jobs. They work to close so that adults with young children can go home to care for their kids. Moms & dads get to be home for bed times. High school & College students sweep floors and close up shop.

Back in my days kids would hang around the school. Smoke and drink. 

Hopefully, they go home the way they're supposed to.

Cruising has always been popular. Also, parking or just hanging out at each other's homes.

My city has teen clubs.  Just like a real club except there is no alcohol and there is an age limit.

yes they just hang around street corners with other teens drinking and smoking

If there is an ACTUAL CURFEW of 11:30 pm - that means that all teens should be AT HOME by 11:30 pm.

So - they GO HOME.

Teens caught any place in public could be arrested if you live in a town with an actual curfew based on age limits.  This reduces some of the issues with teens causing problems late at night.  (vandalism done by teens and that sort of thing.)

Teens could also plan to be at someone's home.  If several teens gather for a "party" at a private residence - nothing is going to happen to them unless someone makes a noise complaint.  

But when there is a curfew - teens are not allowed in public locations after the curfew.  (they aren't even suppose to be driving around town after curfew - unless they have proof that their work shift just ended and they are going home)

There is no curfew for a teen that is with an adult.  

The bigger question is are you looking to spy on your kids or just feeling the typical parental urges to worry about your children when they aren't at home? Perhaps you should give them the benefit of doubt and be more trusting in them.

The danger is if you don't that you will push them away by being over motherly and trying to catch them before they fall. If they were older and not living at home would you be worrying about them 24/7? I suspect not. Unless you have reason to believe they are in danger try and be happy and live your life

Nah me and my friends just go on long drives blasting music real loud XD

Drink, smoke pot, graffiti bridges, and have orgies...