And I want to think about some of the ways a city can make it easier and more pleasant to do.
1. A Good Tram Network
Some of the impetus for this is from this video. I'm not sure I agree that trams are the best transit mode (I think there may be a bit of a causal reversal here; good urbanism promotes trams rather than trams actually being helpful to produce good urbanism) but for the purpose I'm talking about today it's true. Good trams are great for exploring a city.
Amsterdam is an excellent example. When I visited I spent more time on trams than anything else because the network is dense (see the multiple trams in that shot?), well-connected (the building on the left is Amsterdam Centraal), and provide a lovely street-level view of the city, which let me get know the cityscape.
You can also see the tram tracks all over the city, which give you an excellent view of where trams go, which is very helpful in navigating the city (also where buses go, since they run in the same lanes).
2. Meaningful Station Stops
This is especially true for termini (not just ending at a giant park and ride) but it holds true for all stations: if there's something at or near a transit station, not just a random placement of stops, it makes exploring much more interesting.
Aquarium is an obvious example in Boston. Not only is the Aquarium nearby (duh) but so is a lot of downtown (which also has additional transit stops of course).
This particular picture is of a bus, but there are multiple transit stations close by the British Library (and of course as we know from the QCA, buses count too).
3. Interconnected Transit
I'd say "multiple modes" but I have also explored cities by a single transit mode quite happily. The key is interconnection: you should be able to get from place to place easily without painful waits or potential missed connections.