This largely commercial city, and second largest in Paraguay is easily accessible from Foz de Iguacu in Brazil. Many Brazilians come into the city to buy electronics and other goods as the costs are far cheaper here, presumably due to lesser taxes. There's a good story in the NYT from 1998 that goes into a bit more detail about the economics of this town: http://nyti.ms/1DhItKb
You can buy just about anything. I saw lots of tables/kiosks set up with knives, throwing stars and toy guns on display, but my driver told me you can buy real guns easily as well - new or used. Supposedly there are a decent amount of drugs that get moved through here as well, so, taking photos was a challenge. My driver was definitely not excited for me to take any photos so I had to restrain myself sadly. He kept telling me "You can realize the photo from the car," as in I can take photos while he's driving so we're not lingering anywhere for too long.
Getting in and out of Paraguay has to be the easiest immigration I've had in a while. At the border, we just drove across, not even stopping to show passports. I guess doing so would stifle the trade that happens too much, so while there are border police monitoring the border, you just drive through slowly and seems it's in and out quite quickly.
Many buildings in Ciudad seemed to be beyond a state of disrepair.