The main door of the Palace, where Pere Falqués combines different architectural styles and wood, wrought iron and bronze, opens onto a hallway staffed by the Corps of Guards or Mossos d'Esquadra (the Catalan police force). From this hallway, another door leads to the entrance hall, part-columned, where there is a security check.

The entrance hall leads to the ground floor of the Palace where you can climb the broad Ceremonial Staircase, or turn left and into one of the courtyards of the old arsenal, now the Sala Auditori (auditorium). Institutional events, conferences and larger receptions are held here, and interviews and debates are recorded for Canal Parlament, the Parliamentary TV Channel. The ceiling of this room, unveiled in 2003, is formed by a huge cut glass dome, the work of André Ricard, featuring the Generalitat crest in the centre. The walls of the courtyard, with its balconies and the original windows by Pere Falqués, reflect the Mediterranean light, especially impressive when viewed from the floor above. The marble floor also bears the crest of the Generalitat.

Returning to the hall, the restrained and functional style of the Auditorium contrasts with the sumptuous Ceremonial Staircase, covered by a glass and wrought iron skylight in Art Nouveau style. The white marble staircase with its balustrade leads up to the first floor where several doors lead off to the offices of the President of the Generalitat and Government Ministers, the offices of Parliamentary staff, the Chief Counsel of the Legal Department, and several committee rooms.

At the top of the stairway is the first floor Hall of Honour, also known as the Saló dels Canelobres (candelabra room) because the main lighting and ornamental elements of this space are eight huge bronze candelabra. The domed ceiling is remarkable for its decoration with allegorical female figures where the use of the trompe-l'oeil technique gives the illusion of a relief painting.

On the facade side of the Palace, the Saló dels Canelobres leads into the Sala de Grups (Groups Room), Parliament's largest committee room, modified during the 6th legislature for holding meetings of the Standing Committee, parliamentary committees and groups and smaller institutional events. The wooden ceiling of this room, decorated in tones of scarlet and dark red, replaces the original, which was almost 15 metres high. Due to shortage of space, this room is temporarily split into two levels; the higher one, at the same level as the building's loft, is divided into three further rooms for committee meetings, preparing parliamentary speeches and working groups. The austere elegance of the original ceiling, with its wood and iron ornamentation, can still be glimpsed from these three new rooms.

On the other side of the Saló dels Canelobres is the Palace's central transept, octagonal in shape and crowned by a dome with a wood and glass skylight inside, where the four arms of the building's inner naves meet. This is where the painting 7 de novembre, by Antoni Tàpies, hangs.

-The two arms perpendicular to the facade contain the Saló dels Canelobres and the Sala de Grups, and the space occupied by the Chamber, respectively; the other two, parallel to the facade, contain the two halls of the Passos Perduts (lost steps). The Saló dels Canelobres leads to the storerooms for the state TVE network, and the Saló Gris (Grey Room) leads to the Catalan TV room, as well as the Parliament press room.

The present Chamber, originally planned by Falqués as the Throne Room, is decorated with wooden handiwork on marble columns with bronze capitols. Refurbished in 1932 as the Saló de Sessions of the Parliament, it was initially furnished with a U-shaped seating arrangement, but in the following year Santiago Marco modified its layout and transformed it into an hemisphere of eighty-five seats covered in orange velvet, with an additional nine seats covered in red velvet for the Government bench. Behind the seats of the Members of Parliament, on both sides of the hemisphere, two boxes were built with marble sides, for use by official guests. Following a gradual incline to the rear of the Hall were rows of benches for the press and the public.

In 1980, benches were placed in the space between the boxes for the fifty additional Members of the restored Parliament, and in 1986, this refurbishment was completed by turning these benches into seats, continuing the semicircular shape of the initial seating. It was therefore necessary to move the boxes for the authorities and official guests back, and space for the public was reduced. Other modifications were made to accommodate new technologies in the Chamber: in autumn 1996 a system of electronic voting was incorporated and in 2002, four cameras were installed to produce an audiovisual institutional record of plenary sessions.

At the back of the chamber, behind the space for the public, a glass door leads to an annex where the Audiovisual Services produce, record and monitor all Plenary and Committee sessions and institutional events held in areas with television cameras. Below is a Press Room for television companies where they can link up to the institutional recording of Parliament and broadcast it as part of their news service.

Two corridors, one at each side of the Chamber, can be reached through the double doors of the Saló de Sessions. At the end of the right-hand corridor is the stairway leading to the public area of the Chamber. In this same corridor, in front of the main door to the right of the Chamber, is one of the offices of the Communications Department.

On the other side, the left-hand corridor also leads to the offices of the Communications Department. Retracing your steps from the two arms perpendicular to the facade, back to the octagonal transept, you can explore the two arms that run parallel to the facade and complete the cross. These form the Hall of the Passos Perduts (Lost Steps), the one on the left known as the Saló Rosa (Pink Room) and that on the right, the Saló Gris (Grey Room). The Saló Rosa, to the left of the transverse nave, has pink marble pilasters and a series of green marble columns set into iron structures decorated with bronze. It leads to the office of the Presidency, and with its remarkable ceiling and decoration is a fit setting for the President's institutional events and official audiences.

To the right is the Presidential Department and the Parliamentary Relations and Institutional Diffusion Department and, between these offices and that of the Presidency, a new corridor leads to one of the two external wings, built by Falqués in 1915 using stone from Montjuïc and red brick. This wing, restored for Parliamentary use during the 6th and 7th legislatures, runs parallel to the central aisle and houses the offices of the Members of Parliament of the Parliamentary groups Socialistes - Ciutadans pel Canvi (Socialists - Citizens for Change) and Esquerra Republicana de Catalunya (Republican Left of Catalonia), split between the first floor and street level.

To the left of the presidential office is a corridor leading to the offices of the Vice Presidents and the left-hand corner of the main facade, where the meeting room of the Presiding Board and that of the Board of Spokespersons are located.

Another corridor with fine ceramic decoration runs from this area to the first floor Hall of Honour, leading to the four offices of the secretaries of the Presiding Board and one of the two interior stairways that unite the three floors of the Palace.

These stairways have exactly the same shape, structure and decoration, and are linked by a corridor that gives access to the rooms immediately above the Sala de Grups. The stairway on the left leads directly to the left wing of the loft. This incorporates a series of large wooden and iron reinforcements to support the roof of the building, which have been taken advantage of for decorative effect. In the left wing are the offices of the Legal Department, the Budgetary Office, the Aran Office, the Office of Legal Text Quality, as well as the Internal Government Management Department, the Office of Comparative Law and Interparliamentary Relations.

The right-hand arm of the first-floor transverse nave, the Saló Gris, with grey marble pillars down its whole left side, leads to the Press Conference Room. Beyond this, at the opposite end to the office of the Presidency, is the Committee Room 1. As at the other end of the Palace, this leads to a new corridor to the other external wing, added by Falqués, with the offices of the Parliamentary groups for Convergència i Unió (Convergence and Union) and for Partit Popular de Catalunya (People's Party of Catalonia), as well as the Mixed Group.

At the start of this corridor, beside Committee Room 1, is another hall and stairs leading to the media room, from where journalists can follow the institutional broadcast of plenaries, committees and institutional events on closed circuit television.

First floor rooms and some corridors have ornamental ceilings with beams with highly original use of wood, wrought iron, bronze and coloured marble, forming visual combinations of striking beauty. The other corridors are simpler, made of brick and decorated with tiles.

From the Saló Gris some arcades lead on to the Ceremonial Stairway. From beside the first floor hall, an internal stairway leads directly up to the right wing of the building's loft, recovered using the same decorative criteria as in the left wing and equipped to hold the Parliamentary Management Department and the IT Management area, which can also be reached by lift from the ground floor. A corridor links the right and left sides of the loft floor.

Except on special occasions like the Diada (national day), members of the public may not enter the Palace through the main door but must use another door to its right, which also had a security check and reception service.

From the right wing of the Palace, a corridor off to the left leads to the building's entrance hall. This area houses the stewarding services.

Along the corridor to the right are the general photocopying services, the Publications, the publications store and the Language Services, as well as the servers of the IT Department. At the end of this corridor on the right hand side is the Parliamentary Library, whose Reading Room looks out over an exterior courtyard with railings.

In the left wing of the Palace are: Medical Services, and the offices of the Auditing and Treasury Department, the Department of Infrastructure, Equipment and Safety, Educational Services, and the Parliament shop and the new bar/restaurant (opened in 2008), which opens onto another exterior courtyard with railings.