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());
}