Housing around Lisbon

For long stays:

• casa.sapo.pt: Apartments, houses and more in whole Portugal.
• alojamento: Similar to the above, but restricted to Lisbon itself, not even covering all suburbs.
• Erasmus
• Ocasião: online flee market
• remax apartments: commercial ...
• BPI

For short stays:

• Lisbon Youth Hostel (close to IST)
  Rua Andrade Corvo, 46
  1050 - 009 Lisboa
  Tel.: +351 213 532 696
  Fax: +351 213 537 541
  e-mail: lisboa@movijovem.pt
• Youth Hostel - Parque das Nações
  Via de Moscavide, Lote 47 - 101
  1998 Lisboa, Expo
  Tel.: +351 218 920 890
  Fax: +351 218 920 891
  e-mail: lisboaparque@movijovem.pt
• There is also an IST-student-residence, but I am not sure if they let also postdocs stay for at least a couple of weeks.