What's worth doing near this exact spot

You're fixed to a hotel, a conference venue or someone's spare room.

I am staying at a fixed location and cannot easily move. Tell me what is genuinely worth doing within reach.

Give me three tiers:
1. **Ten minutes on foot.** Things I would do on an ordinary evening without planning.
2. **Half an hour away.** Worth a short journey, good for a free morning.
3. **One thing further out** that would justify a proper half day, if any. If nothing does, say so.

For each: what it is in one line, why it is worth it, and roughly when it is best to go. Do not invent opening hours, ticket prices or transit times. If a place may have closed or changed, say that I should confirm it exists before travelling to it.

Where I am staying:
How much free time I have:

During and after the trip. Layovers, days that fall through, what is worth doing nearby, and writing it down afterwards.