The Metro (Underground) network of the Spanish capital (approx. 6. 5 million inhabitants in the urban area) is one of the world's greatest: 13 lines run on a system length of about 300 kilometres.

In addition, there are three tangential lines with a length of almost 30 kilometres, which are operated as a light rail with low floor cars. To avoid the term "Tranvía" (Tram), these routes are called "Metro Ligero" (Light Metro).

Operator of the Underground is → Metro de Madrid S.A., for the operation of the light rail the companies "Metros Ligeros de Madrid S.A." (line ML1) and "Metro Ligero Oeste, S.A." (lines ML2 and ML3) were founded.

The city of Barcelona is capital of the autonomous region Catalonia in Spain and has about 1.6 million inhabitants (over 3 millions in the metropolitan area). After the first tramway network had been abandoned in 1971, the tram was reopened in 2004. Currently there are two tramway networks which are not connected with each other. There´s also a short tourist line, called the "Tramvia Blau". The Metro (Underground) Barcelona operates on a network of more than 120 kilometers. It is an unusual feature of the Metro that there are two operators (the municipal TMB and the Catalan railroad company FGC) and three different track gauges: The line 1 runs on broad gauge (1,668 mm), the line 8 on metre gauge, all other lines on standard gauge (1,435 mm).

Operator of the tramway routes is the "Tramvia Metropolità S. A.", all other modes of transportation (apart from three metro lines, see above) are operated the → TMB (Transports Metropolitans de Barcelona).

Bilbao has only one tram route. It runs in the city centre and has a length of approx. 5 kilometres. It was opened in 2002, after the first tram network was abandoned in 1964.

The Metro Bilbao consists of two lines, which share a common route through the city centre. It has a system length of about 45 kilometers long and is running on metre-gauge tracks as well as the tram.

While the → Metro Bilbao is operated by a same-named company, the tram belongs to the operator → Euskotren, which runs an extensive metre-gauge railway network in the Basque Country.

Seville, the capital of the autonomous community of Andalusia in southern Spain, has about 700,000 inhabitants. Until 2007, public transport in the city was handled only by buses, since then there is a short tram line in the centre as well as an some 18 kilometre long metro line, which is operated by low-floor vehicles.

The tram is operated by → TUSSAM (Transportes Urbanos de Sevilla), the subway by → Metro de Sevilla Sociedad.

The network of "Metro Valencia" has a system lenght of about 150 kilometres. It is used both by low-floor tram lines as well as by high-floor metrolines. A special feature is the integration of four narrow-gauge, largely single-track railway lines into the metro network. This is why the inner city underground lines were also built with metre-gauge tracks. These outer branches reach out very far of the city (line 1 is 98 kilometres long) and are served every 30 to 60 minutes.

The network is operated by FGV (Ferrocarrils de la Generalitat Valenciana) under the brand name → metrovalencia.

The Tram Alicante (→ TRAM Metropolità d’Alacant) consists of four lines, which operate on one route with two branches. The main route runs underground in the town centre, outside the city mostly on a converted former railroad line (metre gauge). Therefore the trams run partially as a railway. The main route Alicante - Denia has a length of more than 90 kilometres and is still served by diesel motor units in the northern part.

Operator of the system is a company named FGV (Ferrocarrils de la Generalitat Valenciana).

Zaragoza is located in the eastern part of Spain on the river Ebro, has nearly 700,000 inhabitants and is the capital of the Aragon region. The city opened an approx. 12 kilometres long tram line in 2011. An earlier tramway network was abandoned in 1976. Further routes are planned.

The tram is operated by a consortium called → Los Tranvías de Zaragoza.

The city of Parla is located about 20 kilometers from the Spanish capital Madrid, is the end point of a Madrid Cercanías (suburban railway) line and has approx. 120,000 inhabitants. Since 2007, the city has a tram line which connects the majority of Parla's districts with the Cercanías as a ring route. A round on the ring, which is served in both directions, is 8 kilometres long and takes 20 minutes.

For the operation of the tram, the company → Tranvía de Parla S.A. was founded.

The city of Palma (Majorca) has opened its metro in 2007. It runs on metre-gauge tracks to ensure compatibility with the railway line to Inca. Since 2013, this route is also used by metro trains until Marratxí (line M2) after the electrification of the railway line. The ridership on the main line M1 is rather small outside the lectures at the university, this is why the metro runs only every 30 minutes during off-peak times. On Sundays and bank holidays, the metro is even out of service.

The metro is operated by SFM (Serveis Ferroviaris de Mallorca, this company is also the operator of the railway lines to Manacor and Sa Pobla) under the authority of → TIB (Transports de les Illes Balears).

The Sóller tram connects the town with the district of Port de Sóller and has a route length of almost 5 kilometres. It was built in 1913 together with the railway line from Palma de Mallorca to Sóller, so it also has the same exotic gauge as the railway: 914 millimetres (3 feet).

The tram is operated by the operator of the railway line, the → "Ferrocarril de Sóller S.A.".

The Portuguese capital has a small tram network with a length of only about 25 kilometres. Only on route 15E low-floor trams from the 1990s are in service, the other four lines are operated by the well-known modernized old cars, but serve more tourist purposes than a serious public transport. The track gauge is 900 mm.

The most important transport system in Lisbon is the Metro, which has a system length of 45 kilometres. It was opened in the 1950s and continuously extended. The Metro network consists of four lines distinguished by colors instead of numbers.

Buses, trams and three funiculars are operated by the municipal company → Carris, the metro by → "Metropolitano de Lisboa, EPE". The tariff system is somewhat confused, not all tickets are accepted on all means of transport.

With approx. 250,000 inhabitants, the city of Porto is the second largest city in Portugal. It has a tram system with a length of approximately 70 kilometers, which is known as Metro do Porto and runs underground in the city centre.

There are also three heritage tram lines, but they serve mainly tourist purposes and are operated by tramcars from the 1940s in a 30 minutes headway.

Operator of the light rail and the funicular is → Metro do Porto S. A., the buses and trams are operated by → STCP (Sociedade de Transportes Colectivos do Porto, S.A.).

"Metro Sul do Tejo" is a tram network in the cities of Almada and Seixal on the southern coast of the river Tejo opposite the capital Lisbon, which is built partial segregated from the streets. It was opened in 2007, is 13.5 kilometres long and is served by three lines.

The network is operated by a company named → Metro Transportes do Sul SA (kurz MTS).