Level

private void Getinfo_Level(Document document)
{
    StringBuilder levelInformation = new StringBuilder();
    int levelNumber = 0;
    FilteredElementCollector collector = new FilteredElementCollector(document);
    ICollection<Element> collection = collector.OfClass(typeof(Level)).ToElements();
    foreach (Element e in collection)
    {
        Level level = e as Level;

        if (null != level)
        {
            // keep track of number of levels
            levelNumber++;

            //get the name of the level
            levelInformation.Append("\nLevel Name: " + level.Name);

            //get the elevation of the level
            levelInformation.Append("\n\tElevation: " + level.Elevation);

            // get the project elevation of the level
            levelInformation.Append("\n\tProject Elevation: " + level.ProjectElevation);
        }
    }

    //number of total levels in current document
    levelInformation.Append("\n\n There are " + levelNumber + " levels in the document!");

    //show the level information in the messagebox
    TaskDialog.Show("Revit",levelInformation.ToString());
}

Private Sub GetLevelInformation(element As Autodesk.Revit.DB.Element)
    ' Get the level object to which the element is assigned.
    If element.LevelId.Equals(ElementId.InvalidElementId) Then
        TaskDialog.Show("Revit", "The element isn't based on a level.")
    Else
        Dim level As Level = TryCast(element.Document.GetElement(element.LevelId), Level)

        ' Format the prompt information(Name and elevation)
        Dim prompt As [String] = "The element is based on a level."
        prompt += vbLf & "The level name is:  " + level.Name
        prompt += vbLf & "The level elevation is:  " + level.Elevation

        ' Show the information to the user.
        TaskDialog.Show("Revit", prompt)
    End If
End Sub

Private Sub Getinfo_Level(document As Document)
    Dim levelInformation As New StringBuilder()
    Dim levelNumber As Integer = 0
    Dim collector As New FilteredElementCollector(document)
    Dim collection As ICollection(Of Element) = collector.OfClass(GetType(Level)).ToElements()
    For Each e As Element In collection
        Dim level As Level = TryCast(e, Level)

        If level IsNot Nothing Then
            ' keep track of number of levels
            levelNumber += 1

            'get the name of the level
            levelInformation.Append(vbLf & "Level Name: " + level.Name)

            'get the elevation of the level
            levelInformation.Append(vbLf & vbTab & "Elevation: " + level.Elevation)

            ' get the project elevation of the level
            levelInformation.Append(vbLf & vbTab & "Project Elevation: " + level.ProjectElevation)
        End If
    Next

    'number of total levels in current document
    levelInformation.Append(vbLf & vbLf & " There are " & levelNumber & " levels in the document!")

    'show the level information in the messagebox
    TaskDialog.Show("Revit", levelInformation.ToString())
End Sub