Using Regex to extract part of a string

You can use Match.Groups property.

For example:

    var testString = "content/landdata/files/Albuquerque_123.zip";
    var regex = new Regex(@"content/landdata/files/([A-Za-z_-]+)_[0-9]+\.zip");
    Console.WriteLine(regex.Match(testString).Groups[1]);

?: means non-capturing group so get rid of it in the group you actually want to capture.

(?!content/landdata/files/)(?:[A-Za-z_-])*[_][0-9]{1,}(?!\\.zip)

should be

(?!content/landdata/files/)([A-Za-z_-]*)_[0-9]+(?!\\.zip)

... and then you can just query the Groups property of the match.

Tested here

Could you give a bit more context in regards to "getting rid of the _123?"

My understanding of what you are asking for is as follows: You are essentially just trying to remove the _123 from the regex'd string so it becomes /content/landdata/files/[City Name]

So if this is the case, perform a substitution on the _123.

public class Example
{
   public static void Main()
   {
      string pattern =  "_123";
      string output = Regex.Replace(input, pattern, "");

      Console.WriteLine("Output: " + result);                             
  }
}

I didn't really test the above code, and there may be issues with it. There is probably also a better way to do this.

This works for me - puts the city in the capturing group (removed the ?: and move the * inside the group from yours)

content\/landdata\/files\/([A-Za-z_-]*)[_][0-9]{1,}(?!\\.zip)

It looks like you are almost there. Consider the following regex...

(?!content/landdata/files/)(?:[A-Za-z_-])+(?=[_][0-9]{1,}\.zip)

Good Luck!