provenance/mona_lisa_theft/1 matches the site

public static Activity Theft_Of_Mona_Lisa()
{
    var theft = new Activity()
        .WithContext()
        .WithId("https://linked.art/example/provenance/mona_lisa_theft/1")
        .WithLabel("Theft of Mona Lisa")
        .WithClassifiedAs(Aat.ProvenanceActivity);

    theft.Part = [
        new TransferOfCustody
        {
            TransferredCustodyOf = [
                new HumanMadeObject()
                    .WithId("https://linked.art/example/object/monalisa")
                    .WithLabel("Mona Lisa")
            ],
            TransferredCustodyFrom = [
                new Group()
                    .WithId("https://linked.art/example/group/louvre")
                    .WithLabel("Louvre")
            ],
            TransferredCustodyTo = [
                new Person()
                    .WithId("https://linked.art/example/person/peruggia")
                    .WithLabel("Vincenzo Peruggia")
            ]
        }.WithClassifiedAs(Aat.Term("300055292", "Theft"))
    ];

    return theft;
}

• 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 activity = new Activity
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/provenance/mona_lisa_theft/1",
    Label = "Theft of Mona Lisa",
    ClassifiedAs = [Aat.ProvenanceActivity],
    Part =
    [
        new TransferOfCustody
        {
            ClassifiedAs = [Aat.Term("300055292", "Theft")],
            TransferredCustodyOf =
            [
                new HumanMadeObject
                {
                    Id = "https://linked.art/example/object/monalisa",
                    Label = "Mona Lisa",
                },
            ],
            TransferredCustodyFrom =
            [
                new Group
                {
                    Id = "https://linked.art/example/group/louvre",
                    Label = "Louvre",
                },
            ],
            TransferredCustodyTo =
            [
                new Person
                {
                    Id = "https://linked.art/example/person/peruggia",
                    Label = "Vincenzo Peruggia",
                },
            ],
        },
    ],
};

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.