Most Efficient You can rent bicycles at most railway stations, and many streets have designated bike lanes. Cost From $8.50 a day.
Scenic but Slow With more than 150 canals in the city, "canal buses" are ideal for exploring. Take the Museumboat (www.lovers.nl), which visits most sites, including the Anne Frank House, the Rijksmuseum, and nine other landmarks. Cost $18 for an all-day pass.
Most Efficient The subway is well maintained and easy to use, with new service to Barajas airport. Trains run until 2 a.m. Cost $7.40 for 10 tickets.
Scenic but Slow A 30-minute aerial tram ride (www.teleferico.com) links the Paseo Pintor Rosales train station to Casa de Campo, west of Madrid. The journey takes you over the Plaza de España, Palacio Real, Templo de Debod, and Parque del Retiro. Cost $5.80 for a round-trip.
Most Efficient Subway trains typically leave every two minutes during rush hour and every five minutes at other times. The last ride is at 1 a.m. Cost $3.85 for a day pass.
Scenic but Slow Trams are a crowded but fun way to ascend the city’s hills; most routes run late at night. Nos. 15 and 28 pass through the historic district and along the waterfront to the cultural center of Belém. Cost $3.85 for a day pass.
Most Efficient The Métro runs until 1 a.m. through eight zones. Nos. 1 and 2 serve the city center, where you’ll find most sites. Cost Day passes from $10.
Scenic but Slow For the best sightseeing, take the Batobus boat (www.batobus.com), which makes eight stops along the Seine, from the Eiffel Tower to the Jardin des Plantes. Cost Day passes from $13.
Most Efficient The Tube serves 275 stations in six zones, including Heathrow, Gatwick, and Stansted airports; trains run until 12:30 a.m. For real-time travel news, maps, and schedules, visit www.tfl.gov.uk. Cost Day passes from $7.70.
Scenic but Slow Buses are perfect for seeing the city, and many run every 15 minutes, 24 hours a day, 7 days a week. Cost Day passes from $6.
Most Efficient Cabs are inexpensive and accessible, with stands located throughout the city’s historic center. Extra charge for travel after 10 p.m. Cost Average fare $6.
Scenic but Slow New riverboats (www.battellidiroma.it) travel between Tiber Island, in the north, and the Duca D’Aosta bridge, near the Olympic stadium, until 7:45 p.m. daily. Cost Day passes from $2.75.