Baffling.

How is it possible that I'm on the 29th floor of a hotel, and yet when I turn the shower on the very first drops of water to come out of the faucet are hot?

When I'm home it can take almost a minute before the water starts heating up, and that only has to flow 50 feet or so from my hot water heater to the shower.

Disclaimer: If the answer involves something complex like structural engineering or "they have a water heater for every room in a hotel" I don't want to know. Just let it remain a mystery.