Discover the highlights of Antigua on a guided tour. Visit the Antigua/Barbuda Museum, take a walk up to the Cathedral, and stroll down to the vegetable market in St. John's. En route to Heritage Quay, enjoy some duty-free shopping. Start your tour with a visit to the Antigua/Barbuda Museum. Then, take a walk up to the Cathedral, which was erected in the 1800s. Afterward, take a stroll down to the vegetable market in St. John's. En route to Heritage Quay, for duty-free shopping, there are a variety of shops and boutiques for shopping including the Vendor's Mall.