There are, broadly speaking, 3 types of accommodation available in Lisbon: pensions (pensões), guesthouses (residenciais) and hotels.
There is a good choice of small, inexpensive pensions and guesthouses in the central parts of the city, to the northern end of the Baixa, around Rossio, Praça dos Restauradores and Praça da Figueira. Further north of here, the streets around Avenida da Liberdade are where you’re most likely to find a cheap bed at
The central Baixa area has a good range of accommodation, but naturally you'll pay a premium for being in the centre of the action - the same goes for lodgings in the Barrio Alto, where you'll also have to beware that the nightlife goes on until the wee small hours, so quiet and solitude will be pretty hard to find!
Budget Accomadation
There are four youth hostels, or pousadas da juventude in and around Lisbon, including one in the city centre, near Rotunda Marquês de Pombal.
The city’s main campsite is in the Parque Florestal de Monsanto, 6km out of the centre, with further sites located near the Atlantic beaches.