object/nightwatch/10 matches the site

public static HumanMadeObject Nightwatch_10_Color()
{
    var nightWatch = new HumanMadeObject()
        .WithContext()
        .WithId("https://linked.art/example/object/nightwatch/10")
        .WithLabel("Night Watch by Rembrandt")
        .WithClassifiedAs(Aat.Painting, Aat.TypeOfWork)
        .WithRgbColor("#B35A1F", Aat.Term("300127490", "Brown"), "brown");

    return nightWatch;
}

• Metatype classification The second argument classifies the first, not the object: WithClassifiedAs(Aat.Description, Aat.Statement) says this is a Description, and Description is a kind of Statement. The Plain C# form shows the nesting.
• Dimensions and physical description Each helper builds a Dimension with its AAT type, value and unit, or a classification with its metatype: height, width, colour, shape, page count, component count, file size, duration in days.
• Terms outside the registry The vocabulary registry holds only the terms linked.art itself publishes, so a dataset's own concepts, places and people are written with Aat.Term, Tgn.Place and Ulan.Person, giving the id and the label.

var humanMadeObject = new HumanMadeObject
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/object/nightwatch/10",
    Label = "Night Watch by Rembrandt",
    Dimension =
    [
        new Dimension
        {
            Label = "brown",
            Value = 11754015,
            Unit = Aat.Rgb,
            ClassifiedAs = [Aat.Color, Aat.Term("300127490", "Brown")],
            IdentifiedBy = [new Identifier("#B35A1F")],
        },
    ],
    ClassifiedAs =
    [
        new Type("http://vocab.getty.edu/aat/300033618", "Painting")
        {
            ClassifiedAs = [Aat.TypeOfWork],
        },
    ],
};

Generated from the object the example builds: every property that is set, as object initialisers, with the vocabulary constants where a term is in the registry. The fluent helpers are a convenience, not a requirement; this form and the one as written produce the same JSON.