If you are planning on using public transportation during your stay in Hamburg (and we recommend it) think about purchasing a HamburgCARD. This card will provide you with unlimited access to all public transportation in Hamburg and free or reduced admission to museums and sightseeing stops. A day ticket (one adult plus three children) costs €8, and is valid on the day of purchase (or if you start using the Hamburg CARD after 18:00, it's valid all evening and the next day). The three-day ticket costs €18, and the five-day ticket €33; these are valid on the day of first use plus the following 2/4 days. The excellent-value group ticket is valid for up to 5 persons of any age and costs €11.80 for one day or €29.80 for three days and €51 for five-days.