巴塞罗那大眼睛车，上车换票？

With the printed ticket voucher you can board the bus on any stop
during the routes. http://www.bcn.travel/tours/barcelona-hop-on-hop-off-bus-turistic

你可以从你乘坐city bus的第一站换票，然后就可以按照购票天数循环乘坐。