Collegiate Church of the Holy Cross and St. Bartholomew is one of Ostrów Tumski's most beautiful and iconic structures, thanks to a 70m steeple and impressive entry staircase, this curious sanctuary is actually two churches in one. Split over two levels, the building comprises the shorter windows of the Church of St. Bartholomew beneath the soaring windows of the upper level Church of the Holy Cross. The first two-storey church in Silesia, and one of only a few in all of Europe, the church was completed in 1295 as an act of reconciliation ending a long dispute between Duke Henry IV and Bishop Thomas II. For centuries the sarcophagus of Henry IV was housed in the upper Church of the Holy Cross, however today it can be seen on display in the National Museum. Standing outside the church is a large sculpture of John of Nepomuk dating from 1732.
References:The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.