Tour historic Philadelphia on the Victorian Trolley departing from 5th and Market daily. A 90 minute city tour takes you to 20 of Philadelphia's most popular sights. Tickets can be purchased at the Independence Visitor's Center (at 6th & Market) for tickets can be purchased online for a discount. Unlimited on/off privileges and unlimited transfer.
The hours are April-November 9:30 am-5:30 pm except on weekends when it's 6:00 pm; December-March from 10:00 am-4:00 pm. An all day pass is $27.00 for adults; $25.00 for seniors; $10 for children 6-12.
I see these trolleys cruising around town all the time, particuarly in Old City. You can check out the website below for more details, but to summarize, the trolley takes you through Old City, South Philly, Fairmount Park and Center City.