using System;

using System.Collections.Generic;

​

namespace Example

{

    class Base

    {

        public virtual string Foo { get; set; }

        public Base()

        {

            Foo = "Hello world!";

        }

    }

​

​

    class Derived : Base

    {

        List<string> _history;

        public Derived() : base()

        {

            _history = new List<string>();

        }

        public override string Foo

        {

            get

            {

                return base.Foo;

            }

            set

            {

                _history.Add(value);

                base.Foo = value;

            }

        }

    }

    public class Program

    {

        public static void Main()

        {

            var b = new Derived();

            Console.WriteLine(b.Foo);

        }

    }

}