Call ahead and speak with the tour group operator about your use of the walker. A tour group can often accommodate you, but it needs prior notice of your situation.
Bring a friend if possible. A friend who knows how to assist you can make the tourist group experience easier. She can survey the terrain to watch for potential hazards. She can also hold your walker for you when you need both hands. A friend will also wait with you to rest if you cannot finish a tour; no one else from the tour group will have to stay behind with you.
Carry the walker up stairs. Ascend only those stairs with handrails. Walk with the walker and stop half a foot in front of the stairs. Fold the walker or hand it to a friend to fold for you. Grab the handrail. If a friend or tourist group operator can carry the walker for you, step onto the first step with your stronger leg. (If both legs are of equal strength, it doesn't matter which leg you use first.) Pull up your weaker leg. Climb one step at a time. If you want to carry your walker, lift the folded walker and place it on the first step before you lift your legs. Always put the walker down first, your stronger leg second and your weaker leg last. Unfold the walker at the top of the stairs before you ascend the last step. Descend the stairs in the same fashion: folded walker, stronger leg and weaker leg.
Place the walker atop a curb before you step up the curb. Lift your stronger leg up first and your weaker leg second.
