St Mary's, in the centre of Shrewsbury, was founded as a collegiate church, became a parish church after 1548 and was declared redundant in 1987. It is now in the care of the Churches Conservation Trust. The architectural history of the building is highly complex and much remains unsolved. It consists of an aisled nave with a W tower and a S porch, a crossing with a N transept containing the St Nicholas Chapel, and a S transept. The chancel has a S chapel (the Trinity Chapel) and a N vestry. Of this the lower parts of the W tower, the transepts and parts of the lateral walls at the W end of the chancel are 12thc work. The S wall of the S transept was remodelled in the 19thc. The pointed W tower arch is late 12thc, decorated with string course and sculpted capitals. The S nave arcade dates to c. 1200 or a little later, while the N nave arcade is later still. N and S transept doorways decorated with sculpture, both late 12thc. There is a plain W doorway, somewhat earlier than S and N transept doorways. The S porch is of c.1200 and decorated with sculpture both on exterior and interior, leading to S doorway also decorated with sculpture. The church is constructed of local red sandstone.

Anglo-Saxon foundations were discovered during excavations in 1864. This church was rebuilt in c. 1150. In the 12thc and 13thc St Mary's was a collegiate church, later raised to the status of a Royal Free Chapel. Extensive work was carried out between c. 1190 and 1220 and again between 1460 and 1480. The chapels-of-ease of St Mary were Albrighton, Clive and Astley. St. Mary's College was dissolved in 1548, but St Mary's kept its status as a Royal Free Chapel until 1846. The church was extensively restored by S. Pountney Smith in 1867-70.

The Romanesque work in the W tower, i.e the W doorway and the lower parts of the tower arch, are the earliest but differ greatly in style. While the doorway is heavy with early details, pointing to an early 12thc date, the tower arch capitals must belong to the mid-12thc at the earliest.

Nest comes the S porch entrance and its doorway, whose freestanding chevron and crocket capitals belong to the last decades of the 12thc. The S transept doorway belongs to the same campaign. The transept arches are dated on the basis of their tumpet scallops to the 1170s or '80s, but some of the work looks rathere later and may well be restoration. The arcades are the subject of some slight disagreement. Pevsner dates both to the 13thc, while Newman has the S in the late 12thc and the N completed as late as the 1220s. The decoration on the third pier of the S nave arcade (second order, S face) and of the W impost pier is reminiscent of the carving on the capitals of the chancel arch at Wroxeter.

Sedilia with authentic Romanesque ornament are extremely rare, so interpreting the fragment in the S wall of the chancel is significant. Although the church's collegiate status would fit will with the presence of early sedilia (re: St Mary de Castro, Leicester), the fragment is clearly reset so not good evidence of there being sedilia in the Romanesque church.