La Lonja de Zaragoza is a civil structure constructed in Zaragoza (1541–1551) during the first part of the 16th century in the Aragonese Renaissance style as an enclosure for commercial activity. Today, it serves as the City Council's exhibition space.

Juan de Sariena was La Lonja's architect or master builder. He was hired by the municipal council and supported by Hernando de Aragón, the archbishop of the city.

It is Aragon's most significant entirely Renaissance structure. It was also the first to use this design, which was influenced by the Florentine palace from the Italian quattrocento but with elements of Aragonese Mudejar, as evidenced by the ornamentation on the polychrome plaster portraits.

Due to the influence of Islamic art (which can be seen at La Aljafera) and Mudejar, brick, a typical building material in Aragonese architecture, is not regarded as an inferior material.

It has a rectangular ground plan, and the façades are built on three levels—one storey plus an attic or false attic that was used for storing weapons—that do not correspond to the inner volume. A gallery of semicircularly twined arches is present.

Following appeals from the city's merchants and Archbishop Hernando de Aragón, the municipality of Saragossa resolved to erect a civil building for commercial exchanges, which up until that point had been conducted in La Seo and other churches, on February 18, 1541.

Juan de Sariena, a master builder for the city and the Diputación del Reino who had previously completed projects on structures like the Torre Nueva and the Seo de Barbastro, received the project.

Construction was well under way in 1546; all that remained was to finish the roof, which, in accordance with Sariena's plan, included a "lantern-like tower" as its centre crown. The death of the architect Juan de Sariena the year before made matters much more difficult for the master builders of Zaragoza at the time, including Alonso de Leznes, Gil Morlanes el Joven, and master mason Juan de Segura. In 1549, it was ultimately decided to knock down the tower and cover the construction with a straightforward hipped roof. On November 1st, 1551, La Lonja was declared to be finished.

The commodities exchange was designed as an open-plan interior space with three naves and five bays of the same height, eight columns ringed at 2/3 that support fifteen star-shaped ribbed vaults that are already very low, in response to the functional requirements for a civil building intended for trade. The columns have Renaissance-inspired designs, although the late Gothic style's intricate ribbed structures are still present in the ceiling.

Given that stone is a limited resource in the city, the walls are constructed using the rejola and aljez technique (brick with plaster mortar) in the manner of Mudejar masons. But in the Lonja, a band of vertical rectangles that divides the height of the façade in half on the exterior, supported by a moulding or cornice embellished with dentils, has taken the place of the ornamental patterns typical of Aragonese Mudéjar religious buildings. A simple pillar divides a charming gallery of double arches on the upper floor of the exterior walls that hold twin windows that were once covered in tiny pieces of leaded glass (rare until the 18th century). Today, these windows have been rebuilt with alabaster plates. In the tympanum created by the twin arches, below the windows, and in the niches of the oriel windows at the top of the panels, there is a polychrome ceramic medallion with ornamental portraits. At each corner of the structure, four little lanterns decorated with Mudejar tile form the façade's crowning features. Three wide doors with circular arches that flare out in an arrangement resembling archivolts and are framed in a reinterpretation of an alfiz accentuated in the brickwork enter onto the central sections of the ground floor from the lower floor. To create a rhythmic arrangement of a harmonious façade with an original design that reinterprets Italian Renaissance palaces, all the brick highlighting components are sober and add to the façade's harmony.

Gil Morlanes el Joven is credited with designing the interior decoration, which is more conventional and Gothic inside but also has elements of Renaissance style. Aragonese Ionic columns that had a ring or knot in the first third of their length, which gave the new columns that were to be employed in big public structures proportions that were more in accord with classical canons, support the huge, single-height space. In the palaces and noble homes of the Modern Age, this style of column was frequently utilised and spread throughout Aragon. The interior is embellished with sculptural reliefs in the spilling of the window intradoses, carved and multicoloured fleurons in the keystones of the vault intersection, sculptural friezes of grotesques, tondos, and other Roman motifs, and an epigraphic band of Gothic calligraphy written in Castilian, though with a lot of Aragonese in its spelling.

Two stipes of anthropomorphic reliefs flanking the entry adorn the inside doorway. Putti that hold the Saragossa lion rampant coat of arms, which is also seen in the keystones of the fleurons, surround the beginning of the ribs of the vaults. The Charles V imperial coat of arms, flanked by two polychrome and estofado lions, the collar of the golden fleece, pendant columns, and is located in the centre of the walls.

There is a loft-like area that served as the city's arsenal store between the roof and the ceiling. The northwest corner of the area has a spiral staircase leading up to the weapons room. It can be seen as a connected turret in Anton Wyngaerde's 1563 painting of the town's vista.