How to get
From Lisbon Airport
Take the airport shuttle "AeroShuttle" to the Oriente Railway Station (do not take the shuttle called "AeroBus", unless you want to go to the city center). The AeroShuttle bus service runs every 30 mins, between 7am and 11pm, and the journey to the Oriente Railway Station takes 15 mins.
Alternatively, take a metered taxi to the Oriente Railway Station. There are two taxi stands at the airport, one at the Arrivals and the other at the Departures. At the start, the fare on the taxi meter should read 3,25 € (daytime pick-up). Outside the city limits, city fares are charged per kilometer. Transportation of luggage is charged an extra 1,60 €. An additional 20% is charged for services on Saturdays, Sundays, holidays and for nighttime service (9pm to 6am).
Enquire about the fare before taking the taxi.
You can get more information or purchase a Taxi Voucher at the Tourism Information Counter in the airport's Arrivals Hall.
Choose "Alfa Pendular" or "Intercidades" train. For reservations, information, train timetables and ticket prices, please visit http://www.cp.pt/passageiros/en/
From Porto Airport
At the Light-Rail Metro Station in Porto Airport, take E line (Violet) light-rail train to the Campanhã Railway Station in Porto (around 30 minutes). For tickets and prices, please visit http://www.metrodoporto.pt/en/
At Campanhã Railway Station take a train to Coimbra (~1hour to Coimbra). Choose "Alfa Pendular" or "Intercidades" train. For reservations, information on train timetables and ticket prices, please visit http://www.cp.pt/passageiros/en/
Travelling by car
At all Portuguese airports there are several rent-a-car stands. At the airport exit follow the indications to the A1 Motorway towards Porto if leaving from Lisbon Airport, or towards Lisbon ("Lisboa") if leaving from the Porto Airport (the A1 motorway goes from Lisbon to Porto through Coimbra), and take the first exit to Coimbra.
More travel information and detailed directions at Google Maps.