LHR · A long weekend on a ticket · published · checked
72 hours in London from LHR
Seventy-two hours is a weekend, not a tour of southern England. The third day is Greenwich by boat, or a second walk, or a museum you enter on time and leave on time.
The shape
Day one: the ticketed sight and the hotel.
Day two: the river, one direction only.
Day three: Greenwich, or a morning in a single gallery, then Heathrow. If the flight is early, sleep at the airport the night before and do the ambitious day on day two.
Windsor is the only day trip worth naming
It is close, and it still replaces a London day. It does not follow a morning at the Tower. Bath, Oxford, and Stonehenge are how this page fails.
Still one booking
Hold one timed ticket. The boat ticket is the flexible second, because the pier does not care if you are late, within reason, and the return is the same system.
The private Heathrow tour remains the option for people who do not want to learn the railway. On 72 hours you have time to learn the railway.
The border on the way out
You entered the UK, not Schengen. The onward flight still wants three hours, and the terminal on the ticket is the one you go to.