Tynwald is the parliament of the Isle of Man, occupying the Legislative Buildings on Prospect Hill in Douglas. The building contains both chambers of the parliament — the elected House of Keys and the upper Legislative Council — and guided tours are available when parliament is not in session. It's a striking Victorian building, and the visible presence of a working parliament for a self-governing island of just 85,000 people is genuinely unusual.
The Isle of Man is not part of the United Kingdom, though the British Crown is responsible for its defence and international relations. It has its own laws, its own currency (pegged to sterling), its own tax system (no VAT), and its own passport stamps. Tynwald is the visible expression of that autonomy.