Kostel Panny Marie Na Louži was a Romanesque church in Prague's Old Town, near what is now Clam-Gallas Palace. Constructed in the mid-12th century, it served as a spiritual center for the Old Town painters' guild and housed altars dedicated to various saints. The church underwent Gothic renovations to become a three-nave basilica with a spire. It was ultimately destroyed during Josephinian reforms in 1791.

The origins of Kostel Panny Marie Na Louži trace back to the mid-12th century, built in Romanesque style. Its name derived from a vanished settlement called Na Louži, which existed before Prague's Old Town was established in the 13th century. The first documented mention dates to 1268, with Sachaeus as its parish priest. This period marked significant religious and architectural developments in Bohemia under the Holy Roman Empire.

Architecturally, Kostel Panny Marie Na Louži evolved from a simple Romanesque structure into a Gothic basilica featuring a spire. Engravings from the 18th century depict its three-nave design and spiral tower. It was richly endowed with altars dedicated to saints such as Mary Magdalene and Catherine. Notably, Albík z Uničova commissioned an altar for Saints Cosmas and Damian in 1410.

Throughout its history, Kostel Panny Marie Na Louži served various roles beyond being a place of worship. It was the spiritual center for the Old Town painters' guild from 1348, with members gathering at the altar of Saint Luke, their patron saint. The church also had an associated rectory and parish school, and its cemetery extended into what is now part of Clam-Gallas Palace grounds.

Key events in the church's history include its plundering during the Hussite Wars on August 18, 1419, as recorded by chronicler Vavřinec z Březové. This led to significant damage, including the destruction of altarpieces and a marble tomb commissioned by Albík z Uničova. The church's final chapter came with its abolition during Josephinian reforms in 1791, leading to its demolition. Two tombstones were preserved in the Lapidarium of the National Museum, and a bell from 1596 by Brikcí z Cimperka was relocated to Zámrsk.

Today, Kostel Panny Marie Na Louži no longer stands, but its historical significance endures. The site near Clam-Gallas Palace offers visitors a glimpse into Prague's rich past and the architectural evolution from Romanesque to Gothic styles. Although the church itself is lost, its legacy as a spiritual hub for artists and its role in pivotal historical events make it a noteworthy point of interest for those exploring Prague's Old Town.

Visiting the area where Kostel Panny Marie Na Louži once stood provides an opportunity to reflect on the layers of history that have shaped Prague. While the church is no longer there, its story remains an integral part of the city's cultural heritage, inviting visitors to delve deeper into the historical narratives that continue to captivate and inspire.