using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var cities = new List<CityItem>

        {

            new CityItem { City = "City1", Value = 10 },

            new CityItem { City = "City2", Value = 20 },

            new CityItem { City = "City3", Value = 30 },

            new CityItem { City = "City4", Value = 40 },

            new CityItem { City = "City5", Value = 50 },

            new CityItem { City = "City6", Value = 60 },

            new CityItem { City = "City7", Value = 60 },

        };

        var topCities = cities

            .GroupBy(city => city.Value)

            .OrderByDescending(gr => gr.Key)

            .Take(3)

            .SelectMany(gr => gr)

            //.OrderByDescending(city => city.City)

            .ToList();

        foreach (var city in topCities)

        {

            Console.WriteLine(city.City + ": " + city.Value);

        }

    }

}

​

internal class CityItem

{

    public string City { get; set; }

    public int Value { get; set; }

}