In order to enter the park for hiking between the towns, you have to purchase tickets. These will give you trail access and can be purchased at the National Park Service counter at the train station.
These same tickets give you complete shuttle bus and train service between the five towns as well. Even if you don’t hike, this is probably your best travel option at 16€ per person.
We took the train from Vernazza to Riomaggiore and in order to get to the town center, you must walk through a tunnel.
The main street looks similar to the other towns, perhaps with a bit more vertical pitch.
The climb up to the castle is a bit long and on a hot day can be somewhat oppressive.
You cannot miss it, there is a big clock on it!
There are benches and an overlook to the right, once you reach the top.
If you are looking for narrow stairways or alleys, there are plenty of those to explore. After our long hike and short train ride, we actually ate lunch here as well and can recommend Veciu Muin.
So beautiful!