There is actually significant archaeological evidence in Israel and elsewhere. The question is, how do you define a wall? If, for example, you are talking about a hillfort type city or fortification, with rampart and ditch walls at the outset, the earliest of those would have been during the early bronze age, which puts it at roughly 3300-3400 years ago, around the time of Yehoshua. There are a few examples in England and elsewhere in Europe, though most of these date from later.
If you are talking about a city, and a stone or brick built wall, there are a number that likely fit the bill. Tel Hatzor, Tel Meggido, Yerushalayim, Sidon, Tzor, Chevron, Yafo, Dameshek (Damascus).
There are places in modern Iraq or Syria that had walls at one time, like Ur, Carchemish, and Nineveh, but there are no cities above them today.
In Greece, Athens and Argos are the oldest, dating earlier than Yehoshua, in Southeast Asia, Delhi and Luoyang also older.
There are other places, like Mohenjo Daro in the Indus Valley, That are significantly older than these. And other places like Tiahuanaco in Peru that there is a lot of controversy about how old it is.
There is physical evidence to substantiate these locations (and others I haven’t mentioned)
Another thing to consider is the fact that there were likely many towns that built with wood rather than stone, and being organic, the evidence may have long since disappeared. Even up to the middle ages, fortifications were still being built with wood. In places where there is high humidity, the rate of decomposition would be very high, so places like Thailand, or Mexico might have had some fortified, walled cities that have simply disappeared into the jungle.