The corner of Old Town Square outside the Old Town Hall is usually packed with dozens of people touting for business as walking guides; the quality varies. Most operators don't have an office; you can join a walk by just turning up at the starting point and paying your money, though it's best to phone ahead or book online to be sure of a place. Most walks begin at the Astronomical Clock. Besides walking tours you can join some theme tours, horse-drawn carriage tours and vintage car tours. There are also other tours into the surrounding countryside.