@hsl For me, so far it's been Giurgiu, Romania (I myself am Romanian, living in Bucharest). The train line is currently undergoing repairs but has been closed since 2005 when a bridge collapsed at Grădiștea after some floodings. Trains now take a detour in Videle (another town that I do not think I could find anything worth visiting in), and you usually need to switch trains there (even international trains heading from Bucharest to Bulgaria - including Orient Express - take this detour). It takes you 3 hours to get there on a 118 km route, vs a direct 74 km one which at 120 km/h it could be completed in less than 1 hour. On the other hand, the mainline to Giurgiu is currently undergoing repairs and modernization works, so hopefully, by next year you could get quicker to Giurgiu, as well as to Bulgaria by train - although the line won't be immediately electrified on opening as far as I understood.

Giurgiu is pretty tourist unfriendly, and it just seems hard for anyone to just show up there and see on the spot what to visit (although Google Maps did help me though). Especially if you travel alone and you're not Romanian as well, you'll have a hard time because English language guidance is simply non-existent - so do find someone understanding the language. Here is however what I've seen:

• The Clock Tower in the city center - there is now a cozy restaurant on the ground floor of it, however.
• The Giurgiu county History Museum "Teohari Antonescu" (there are English labels, but you'll sometimes feel weird being the only person visiting the museum - it is interesting to visit if you want to know more about the history of my country 🙂)
• The Alleyways (Alei) Park - basically a Central Park with lots of statues of old historical figures, but you'll have to Google them to see more info. In the same park, there was a restaurant where I ate a pizza for ~5$. Quite a bargain given the current prices here, 5 years ago I could get one for the same price even in Bucharest.
• There are some ruins of an old citadel not far from there, but they seem to be undergoing restoration works as well, so you can basically only see them from a distance - and I didn't really see anything noticeable.
• Right next to these you'll find the Bizetz Bridge, allegedly the 1st curved bridge in Europe - again, Google is your friend. There's nothing than a pane with a QR-code on it, partly covered in graffiti. And there's nothing telling you about this bridge, no directions.
• There is the former Giurgiu Sud (South) train station, in which now people live - it still has the older communist coat of arms on it, so you'll notice it quite easily, even though you cannot enter it.
• The Ulysses monument next to the port - Giurgiu is a port city on the Danube, so you could put that on the list as well.
• Giurgiu Nord (North) station is an interesting one, quite big. It seems built in the Stalinist style of the 1950s, with an impressive interior, but - interestingly - with no communist propaganda mosaics. Instead, there are scenes depicting the so-called Vlacho-Bulgarian Empire.

The problem with the latter, as well as the rest of the city, was that there is no public transport. Nothing, nada. And it is a fairly large city. While Giurgiu is a typical downtown station, Giurgiu Nord is, as the name suggests, in the North of the city. Really not ideal if you want to visit by train. As the city is also not that large and important, there are also no Uber, Bolt or other ride-sharing services AFAIK, and no scooters to rent. It's all bring your own transport, I don't know how can people out there move around. I literally walked all the way, and it was tiring as hell. It took me almost one hour to go from downtown to Giurgiu Nord where I took the train back.

Besides that, there seemed to be no pedestrian only places (besides the park) and the people seemed to be the kind of ones that would pickpocket you at the first occasion - so if you go there, do watch your belongings as well.

For me, this seems to be a similar situation with most places in southern Romania outside Bucharest.

And by the way, as I remembered about Bucharest, do not visit the Ferentari neighborhood alone. Especially at night.