TreeNode

using (SPWeb web = SPContext.Current.Web)
{
    foreach (SPWeb topWeb in web.GetSubwebsForCurrentUser())
    {
        TreeNode tn = new TreeNode(topWeb.Name);
        tn.NavigateUrl = topWeb.ServerRelativeUrl;
        this.treeviewProjects.Nodes.Add(tn);
        if (topWeb.Webs.Count > 0)
        {
            foreach (SPWeb subWeb in topWeb.GetSubwebsForCurrentUser())
            {
                TreeNode childNode = new TreeNode(subWeb.Name);
                childNode.NavigateUrl = subWeb.ServerRelativeUrl;
                tn.ChildNodes.Add(childNode);
                subWeb.Dispose();
            }
        }
        topWeb.Dispose();
    }
}