Your guide will meet you anywhere in the Helsinki city center for pickup at a time of your choosing. Climb aboard your private vehicle, equipped with free WiFi, and get started for Porvoo. The journey should take just under an hour.
Once you arrive, take a walking tour of the Old Town, whose layout is typical of the Middle Ages. Amble past low wooden houses, spectacularly well-preserved for how old they are, and see the red warehouses lining the riverbanks. Listen to your guide talk about the trading, fishing and seafaring that is a huge part of the village's history. Stop by the medieval cathedral, built between the 13th and 15th centuries. You get totally undivided and personal attention from your private guide as you explore.
Take advantage of some free time to explore on your own, ducking in to the artisan workshops and other boutiques or just wandering down the narrow streets.
At the end of your time in Porvoo, head back to Helsinki for drop-off at your chosen location.