// retrieve and iterate current selected element
UIDocument uidoc = commandData.Application.ActiveUIDocument;
ICollection<ElementId> selectedIds = uidoc.Selection.GetElementIds();
Document document = uidoc.Document;
foreach (ElementId id in selectedIds)
{
    Element e = document.GetElement(id);
    Wall aWall = e as Wall;
    if (null != aWall)
    {
        // get AnalyticalModelSurface from Structural Wall
        AnalyticalModelSurface modelWall = aWall.GetAnalyticalModel() as AnalyticalModelSurface;
        if (null == modelWall)
        {
            // Architecture wall doesn't have analytical model
            continue;
        }

        // get wall curves
        StringBuilder wallString = new StringBuilder();
        wallString.AppendLine("Wall curves:");
        IList<CurveLoop> wallCurveLoops = modelWall.GetLoops(AnalyticalLoopType.External);
        foreach (CurveLoop curveloop in wallCurveLoops)
        {
            CurveLoopIterator itr = curveloop.GetCurveLoopIterator();
            itr.Reset();
            while (itr.MoveNext())
            {
                Curve wallCurve = itr.Current;
                wallString.AppendLine(String.Format("{0}, {1}", wallCurve.GetEndPoint(0).ToString(), wallCurve.GetEndPoint(1).ToString()));
            }
        }

         TaskDialog.Show("Wall Analytical Model", wallString.ToString());
    }
}

' retrieve and iterate current selected element
Dim uidoc As UIDocument = commandData.Application.ActiveUIDocument
Dim selectedIds As ICollection(Of ElementId) = uidoc.Selection.GetElementIds()
Dim document As Document = uidoc.Document
For Each id As ElementId In selectedIds
    Dim e As Element = document.GetElement(id)
    Dim aWall As Wall = TryCast(e, Wall)
    If aWall IsNot Nothing Then
        ' get AnalyticalModelSurface from Structural Wall
        Dim modelWall As AnalyticalModelSurface = TryCast(aWall.GetAnalyticalModel(), AnalyticalModelSurface)
        If modelWall Is Nothing Then
            ' Architecture wall doesn't have analytical model
            Continue For
        End If

        ' get wall curves
        Dim wallString As New StringBuilder()
        wallString.AppendLine("Wall curves:")
        Dim wallCurveLoops As IList(Of CurveLoop) = modelWall.GetLoops(AnalyticalLoopType.External)
        For Each curveloop As CurveLoop In wallCurveLoops
            Dim itr As CurveLoopIterator = curveloop.GetCurveLoopIterator()
            itr.Reset()
            While itr.MoveNext()
                Dim wallCurve As Curve = itr.Current
                wallString.AppendLine([String].Format("{0}, {1}", wallCurve.GetEndPoint(0).ToString(), wallCurve.GetEndPoint(1).ToString()))
            End While
        Next

        TaskDialog.Show("Wall Analytical Model", wallString.ToString())
    End If