Add Properties to a SharePoint site

SPSecurity.RunWithElevatedPrivileges(delegate()

                   {

                       using (SPSite spSite = new SPSite(siteUrl))

                       {

                           using (SPWeb spWeb = spSite.OpenWeb())

                           {

                               spWeb.AllowUnsafeUpdates = true;

                              

                               //Annoucements List

                               objSPList = spWeb.Lists.Cast<SPList>().FirstOrDefault(l => l.Title.ToString() == Constants.LstAnnouncements);

                               if (objSPList != null)

                                  //spWeb.Properties.Add(Constants.LstAnnouncements, objSPList.ID.ToString());

                                   spWeb.Properties[Constants.LstAnnouncements] = objSPList.ID.ToString();

                              

                               //Project Documents

                               objSPList = spWeb.Lists.Cast<SPList>().FirstOrDefault(l => l.Title.ToString() == Constants.DocLibraryName);

                               if (objSPList != null)

                                  //spWeb.Properties.Add(Constants.DocLibraryName, objSPList.ID.ToString());

                                   spWeb.Properties[Constants.DocLibraryName] = objSPList.ID.ToString();

                               spWeb.Update();

                               spWeb.AllowUnsafeUpdates = false;

                           }

                       }

                   });