Vallby kyrka

The church's oldest section is the western part of the nave, dating from the Romanesque period. During the Folkung era the nave was extended eastwards to double its original length, turning it into a hall church, with the new walls built narrower and taller than the older ones. Around the mid-1400s, brick cross-vaults were added to the interior, requiring supporting arches and wall pillars in the two eastern bays. The porch was added later in the medieval period, and the tower's exact age is uncertain, though it likely followed the vaulting of the nave and existed by 1637, when a spire was added. The present brick sacristy dates from the 1740s, probably replacing an earlier one on the same site.

Inside, visitors can see Renaissance-style wall paintings attributed to an unknown master, believed to date from around 1520 and uncovered and conserved in 1958; they survive in the chancel and the eastern bay of the nave. A well-preserved triumphal crucifix from the 1400s hangs on the north wall of the chancel, decorated with evangelist symbols and a figure of the mourning Virgin Mary above Christ's head. According to Wikipedia, red threads once hung from the figure to represent flowing blood, though it is unclear whether these survive today.

The altarpiece, with its richly carved and gilded frame, was donated to the church in 1740 by Queen Ulrika Eleonora; it was carved by the sculptor Johannes Liung and painted by court painter Georg Engelhard Schröder. Other notable furnishings include a gilded armchair given to the church in 1748, and two of the church's doors — one said, according to local tradition, to originate from the vanished castle of Gröneborg in Lake Mälaren, though this cannot be verified. A newer addition in the chancel is a sculpture of the Virgin Mary.

Among the church's textiles is an unusual medieval chasuble made from Florentine silk damask of the late 1400s, incorporating a princely crown and a diamond ring motif linked to the Medici coat of arms; its lining is North Italian work from the later 1300s, related to some of the cope linings at Uppsala Cathedral. The church also retains an organ case from 1765, though the instrument itself was rebuilt in 1931.

The churchyard is enclosed by a stone wall dating from 1759, with covered gateways on its eastern and north-western sides; a separate bell tower once stood in the churchyard but was demolished in the 1800s when the bells were moved into the church tower itself. Adjacent to the church is a community of the Sisters of Mary (Mariadöttrarnas kommunitet).