En una de les artèries més dinàmiques de la ciutat, l'església de Pompeia encara contribueix a conservar el caràcter senyorial que va tenir la zona en el moment de la seva construcció. Pel seu emplaçament privilegiat, aquesta és una de les obres més populars del seu autor. Com passa en altres obres religioses de Sagnier, el conjunt —format pel temple i el convent annex de frares franciscans (caputxins)— està resolt a través d'un llenguatge neogòtic lliurement interpretat: l'església, de tres naus separades per columnes esveltes, reprèn aspectes de la tradició gòtica catalana, com la nau central d'arcs coberts per bigues de fusta (solució semblant a la capella de santa Àgueda, a l'antic palau dels comtes de Barcelona), mentre que la inventiva de l'arquitecte es fa present als capitells d'estilització floral oa les obertures triangulars. A la façana de pedra destaca el treball escultòric de Josep Llimona: un relleu a la porta i una imatge de sant Francesc d'Assís al gablet superior.

Per la seva banda, el convent (acabat el 1915) és una mica més sobri, en la tradició franciscana de la humilitat, i combina la pedra amb el totxo. Consta de tres crugies, paral·leles a l'alineació de les façanes exteriors; entre elles i la nau lateral del temple es forma un pati irregular amb ornamentació de mosaic. Una de les dependències més destacades del convent és la gran biblioteca de tres pisos (els superiors arrecerats per una barana metàl·lica) i que rep la il·luminació zenital a través d'una claraboia.

El 1936, l'interior del santuari va ser destruït i es va perdre el retaule major, amb pintures de Joan Llimona i centrat per la imatge de la verge de Pompeia, obra del germà d'aquest, l'escultor Josep Llimona (cofundadors ambdós, amb Sagnier, del Cercle Artístic de Sant Lluc). El conjunt va ser reconstruït després de la Guerra Civil per l'arquitecte Pere Benavent, que va procurar tornar-li l'aspecte original a l'interior, encara que també va aprofitar l'ocasió per construir una cripta sota la nau central.

The building is located on the block bounded by the streets Riera de Sant Miquel, Seneca, Minerva and Avinguda Diagonal. The building stands on the corner plot between Avenida Diagonal (number 450) and Riera de Sant Miquel.

The church, which stands perpendicular to Avinguda Diagonal, is the easternmost building in the complex. Attached to one of its sides is the monastery itself, with a series of buildings which, delimiting the angular shape of the plot, are situated around a large triangular courtyard which recalls the traditional monastic layout with a cloister in the centre.
The church, dedicated to the Virgin of the Rosary, is part of Sagnier's Catalan Art Nouveau period of neo-Gothic inspiration, which the architect usually used for the buildings of worship he designed. It consists of three naves separated by slender columns with vegetal capitals and covered with polychrome and gilded wooden beams over pointed arches. The central nave, higher than the side naves, has a series of openings that give it light in the form of portholes. On the other hand, in the side naves, only the one facing the courtyard of the complex has windows (it receives light directly from this patio), while the one on the other side has none, as it is a partition with the neighbouring property.

The chancel has a hexagonal floor plan. The upper band of the headwall is configured as a body of pointed windows with tracery and is covered with a ribbed vault. At the foot of the church is the heart of the church, which has two levels. The lower one is configured as a portico, as it is precisely where the entrance to the church is located, and is covered with a forging with polychrome, gilded wooden beams that form the base of the upper floor where the organ is located.

The walls are covered with a plaster that imitates rows of ashlars and is spatially ornamental in the upper part of the arches.

The façade, also following the Gothic style, stands out for its verticality, accentuated by the entrance doorway to the church. This main entrance is crowned with a gable with a relief on the tympanum, carried out by Josep Llimona. The image of Saint Francis of Assisi on the upper part is by the same artist. The central body of the façade is framed by two turreted structures which, inside, correspond to the side naves. Of these elements, the one that adjoins the neighbouring property is only half a storey high, unlike the other, which is higher, giving rise to the church's bell tower.

The façade of the monastery, which faces Riera de Sant Miquel and the chamfer with Avinguda Diagonal, is made of exposed brick combined with stone and stands out for the robustness of the constructive elements that make it up, especially the columns of the openings. Access to the monastery is through a door located on the chamfer of the building which, flanked by two windows with sculpted lintels, is completely framed by a lowered pointed arch. This first section of the chamfer is made of stone and is complemented by a gallery of windows set between very sturdy columns with short, wide shafts. From this level onwards, the facing is made of brick, reserving the stone for the corners, the window frames and the crowning of the façade. As far as the side façades are concerned, the same arrangement of materials is maintained depending on the height level - stone on the ground floor and brick on the rest. The gallery of windows on the ground floor, the two storeys of brick windows with stone lintels and the sill developed at the ground floor level stand out.

One of the most important spaces in the complex is the library, also designed by Sagnier, which has little to do with the neo-Gothic style of the complex. It was conceived as a three-storey metal structure, accessed via a spiral staircase, which receives zenithal lighting through a skylight.