Follow the process below to publish content from another URL in a ContentPlaceHolder Control..

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
 
<asp:Literal runat=server ID="ltlContent" />
 
</asp:Content>
 
protected void Page_Load(object sender, EventArgs e)
      {
 
            try
            {
 
         WebRequest wReq = WebRequest.Create("http://yahoo.com");
         WebResponse mRes = wReq.GetResponse();
         StreamReader sr = new StreamReader(mRes.GetResponseStream());
         string sHTML = sr.ReadToEnd();
         sr.Close();
         mRes.Close();
 
             if (sHTML != string.Empty && sHTML != null)
              {
                ltlContent.Text = sHTML;
              }
 
            }
 
            catch (Exception eX)
        {
          Response.Write(eX.Message);
         }
       }