The church of San Antón, or San Anton eliza in Basque, is a late 15th-century Gothic Catholic church situated in the Biscayan city of Bilbao, in the Basque Country. Its specific invocation is San Antonio Abad. It is the most well-known church in Bilbao due to its history and location on the banks of the Bilbao Estuary, close to the same-named bridge, the Ribera market, and the ancient Town Hall, in the centre of the Old Quarter, making it appear on the town's coat of arms.

On the same location, there was a fish market or a warehouse for river goods around three hundred years before the chapel was constructed. The previous fish market was absorbed into the newly developed urban area when Don Diego López V de Haro, the eleventh lord of Biscay, awarded a Town Charter to the settlers on the banks of the river Ibaizábal in 1300. Alfonso XI of Castile constructed a fortification and a protective wall on the location in 1334. The wall also served as a dyke to prevent floods. Archaeological investigations in 2002 uncovered the wall's foundations, which are now visible behind the church's altar.

This portion of the wall and the stronghold were quickly destroyed and replaced by a church erected in 1433 and dedicated to Saint Anthony the Abbot. It was a rectangular, single-nave structure with a vaulted ceiling. The foundations of the earlier church's chancel, which were constructed with rectangular sandstone ashlars and had a polygonal shape, can be seen behind the altar of the current church, overlaid on the wall's remnants. The first church was in use for around 50 years before it was decided to enlarge it in 1478 since it was getting too small to hold the increasing number of parishioners. The second edifice, which was practically quadrangular in plan and continued to be Gothic in style, was finished in its basic form in the early 16th century, approximately 1510.

The Renaissance-style main portico was started in 1544 by Juan de Garita and finished in 1546–1548 by a group of sculptors under the direction of the Franco–Flemish sculptor Guiot de Beaugrant. Stonemason Juan de Láriz built the balcony in 1559. The three chapels belonging to the Gospel nave (north), the smallest of which is next to the portico, are Gothic-Renaissance structures from the second third of the 16th century. Juan de Iturburu created the Baroque bell tower, which Manuel de Capelastegui hired to build and finished in 1775. The parish offices that encircle the east wall of the church, the auxiliary portico, and the sacristy were the final additions. They were constructed in 1902 in the Neo-Gothic style, to an Enrique de Epalza's design.

The church's interior served as a cemetery from the time it was founded until the 19th century. The church has seen numerous tragedies throughout its history, the most recent being the devastating floods of 1983, which swept away much of its interior décor and tore off doors and gates. San Antón was designated a Cultural Asset of Interest with the category of National Historic-Artistic Monument on July 17, 1984.

The existing church has three staggered naves with four bays each. The side naves have basic ribbed vaulting, while the main nave has composite ribbed vaulting. The principal chapel has the most ornate ribbing, with double tercelets. Except for the semicircular ones in the first bay, all the supporting arches are pointed. The free-standing supports consist of cylindrical core pillars to which columns supporting the vault's ribs and pilasters for the former arches are attached. Similar-looking semi-pillars are fastened to the walls. With the exception of those in the Gospel nave (north), which are ornamented with balls, all of them have plain continuous capitals. Only the corbels under the choir and the first bay of the opposite nave depart from this austerity and are embellished with zoological motifs.

The triforium, which is of small proportions and is in the shape of a running gallery and crosses the wall that separates the main chapel, is located in the walls that enclose the central nave beneath the windows. The triforium in Santiago Cathedral's triforium has a nearly comparable layout. The temple includes some odd features, such as a straight chancel and no apse, as well as a chamfer at the head of the south nave that allows the estuary's waters to flow through.

Twelve elements make up the main altarpiece, which is a set without masonry. There are seven paintings by contemporary Bilbao artist Ignacio Garca Ergüin, and five sculptures, including two reliefs representing the Washing of the Feet and the Last Supper in the predella, two round sculptures of St. Peter and St. Paul in the middle section, and a crucified Christ in the attic. The two bultos and the two reliefs were created by Esteban de Velasco in accordance with Martn Ruiz de Zubiate's traces as part of a Romanesque altarpiece that is no longer in existence and dates to the latter years of the 16th century. The sculpture of the Christ dates from the early Spanish Renaissance. A 15th century Gothic polychrome wood carving of Saint Anton may be found right next to the presbytery, right by the front door.

The provosts Lezama-Leguizamón, Martnez de Recalde, and Ibaseta, in that order, funded and constructed the three private chapels.

The oldest chapel is Santa Luca, and the earliest records of it date from 1530. It was designated as the Consulate's official chapel at the end of the 17th century. A unique grille from the 17th century that has two pieces and is crowned with an airy cresting with Provost Leguizamón's coat of arms blocks entrance to it from the nave. The Immaculate Conception figure and a carving of Saint Agatha are housed in the attic of a rococo altarpiece from the latter part of the 18th century, which is the remnant of an altarpiece by Antonio Alloitiz created in 1664. Two paintings by Manuel Losada, created in 1907, depicting Saints Valentine of Berriochoa and Ignatius of Loyola, the patron saints of Biscay, are shown on its sides. A canvas from the middle of the 17th century hangs on one of the walls and surprises visitors by showing the circumcision of Jesus in Bethlehem's stable rather than the church, as is customary.

The former chapel is attached to Nuestra Seora de la Piedad's chapel. Although the altarpiece and grille are older, it was founded in 1554. This Renaissance-style piece was created in 1538. It is among Biscay's finest Renaissance grille specimens. The altarpiece of the Pietà is a magnificent Plateresque creation that bears a resemblance to the works of Guiot de Beaugrant. However, the reliefs on the predella and the side streets were not created by Guiot de Beaugrant, who may have been the creator of the Pietà's central motif—an expressive image of the Virgin holding the dead Christ. A picture depicting the visit of Saint Anthony Abbot to Saint Paul the Hermit, from the middle of the 17th century, is located to the left of the altarpiece.

San Roque Chapel is the final and smallest chapel among the trio. A elegant carving of the eponymous saint and the nearby San Sebastián is on exhibit in a sepulchre in a triumphal arch. It is most likely the creation of court sculptor Juan Pascual de Mena, who must have worked on it between 1754 and 1756 while he was in Bilbao.

Domingo de Garita, a skilled builder, and Juan de Lete, a notcher, constructed the choir, which is located at the base of the cathedral, in the final quarter of the 16th century. It houses a 1901 Parisian Cavaille-Coll organ. Two statues of Saints Cosmas and Damian, created in 1664 by the sculptor Antonio de Alloitiz, are located beneath the choir.

An image of Saint Anthony of Padua with Child, a rococo piece credited to Juan Pascual de Mena, may be seen in the first portion of the Epistle aisle, in a stone niche. The Virgin of Begoa, the patron saint of Vizcaya, is shown in a contemporary rendition inside a wide arch that has been hollowed out in the wall. This sculpture was created by Larrea. A painting to the right of it, presumably from the end of the 17th century, is devoted to the Assumption of the Virgin.

The portico on the façade is a lovely example of Renaissance architecture, decorated with fantastical elements and iconographic statements. The triumphal arch that separates the two pairs of columns flanking St. Peter and St. Paul serves as its focal point, and above it, guarding it, is a tribune or balcony that looks out onto the square.

A giraldillo, an allegory of faith carved by the Cantabrian Gerónimo de Argos, tops the dome and lantern of the Baroque bell tower, which has an octagonal body with pinnacles on volutes at the angles. The twin pair of flying buttress arches that discharge the tensions produced by the central nave—which nearly doubles the height of the side naves—onto two buttresses raised like pilasters—stand out on the outside of the Epistle's nave (to the south).