The open-top double-decker that loops the old town, the Panecillo and the modern north. It is the least adventurous thing in this guide and it is genuinely useful on a first afternoon in a city at 2,850 metres, when walking uphill is harder than it looks.
Two kiosks sell tickets: one beside the Plaza San Francisco in the old town, open daily 09:30 to 17:30, and one on Shyris at Naciones Unidas in the north. They publish no phone number at all — the contact page states plainly that the WhatsApp line takes messages, not calls.