Heathrow Airport is the 2nd busiest airport in the world and the largest and busiest in the UK. It's located about 27 km from central London which it serves.
It consists of four large terminals - Terminal 2, Terminal 3, Terminal 4 and Terminal 5. The terminals are connected by trains and buses. They all have various types of restaurants, internet kiosks, business facilities and more.
Each terminal has its own spectator area, though only Terminal 4 has an observation deck.