
JHE friend Dr. Samuel Gruber has posted on his blog a detailed discussion about the multiple layers of painted decoration in the 16th century Remu synagogue in Krakow that makes a fascinating and informative read.

The Remu, built in 1551, was devastated during WW2, but restored and rededicated in 1957. It was long the only fully functioning synagogue in Poland.
Until a new restoration in the 2010s revealed colourful wall and ceiling paintings, it was a space whose walls and ceiling were a featureless white expanse, showing virtually no decoration.
The restoration in 2010-2013 revealed very colorful paintings, most apparently, he believes, from the 1920s and 30s — including representations of the Zodiac signs as well as images of Biblical landscapes and imaginary animals.
They also include much earlier painted prayers and inscriptions.
In his article, Sam provides photos and discusses how conservators chose to preserve — and, importantly, present — these paintings, which in their diversity demonstrate artistically the passage of time and changing sensibilities through the centuries.
The new look of the Remu is dazzling, but it is confusing. The conservators made some subjective choices about which parts of which mural layers to fully conserve and present. To my eye there are at least three levels of painted decoration, and possible more. So rather than being a near-embodiment of the architectural style of its time (1570s), the Remu now is instructive about the passage of time, and of changing tastes in synagogue decoration. The type of conservation that creates an historical collage, has been in employed in the old churches for many decades.
He cites an important article (“Ars brevis, vita longa: On Preservation of Synagogue Art,” Studia Hebraica 9-10 (2009-10), 91-111) by art historian and professor at Bar-Ilan university Ilia Rodov, who discusses “the tension between ‘restoring’ an interior as a museum or as an active synagogue. Museum goers expect a lesson in history. Worshipers prefer a unified and preferably uplifting space.”
(We have discussed how some restorations attempt to bring back synagogues to their “original” pre-WW2 state, which others, such as in Lostice, CZ, and Samorin and Trnava, Slovakia, have been restored in a way that shows evidence of the damage they have undergone.)

The conservators at the Remu synagogue, he writes, “chose to sample history rather than recreate or invent out of whole cloth a unified decorative program.”
He laments that there does not seem to be any written information about the paintings available at the synagogue, nor do tour guides appear to have much to say about them.
Read our article about restorations of synagogues that show damage