Pliska - 100 years of archaeological excavations
R. Rashev, Ya. Dimitrov

III. The legacy of Pliska

    10. Sculptural decorations

Most of the inscriptions from the pagan times were cut into columns erected at prominent places in Pliska. Besides the texts they carried, the columns contributed to the environment around the stone palatial buildings. The columns carrying the names of the East Thracian fortresses conquered by khan Krum were regarded as triumphal signs and as symbolic trophies captured from these towns.

A marble column bearing the name of the fortress of Gariala

Names of fortresses (Burdidzo, Didimotihon, Redesto) from columns. SVaklinov, p. 133

Similar was the function of the large column, found by K. Skorpil at the hill of Vezir tepe – the highest point of the plains to the south of the earthen rampart. Its diameter of 1 m would correspond to a height of 8-10 m. Its crudely polished surface has a shallow helical flute which makes it resemble the similarly decorated Roman-Byzantine triumphal columns. The poor quality of the marble used betrays a local origin, probably from the quarry in the district of Marcianopolis.

-----> External reference: Ziezi's page about the large column with a helical flute  (in Bulgarian)
In contrast to Preslav, the public buildings of Pliska were poorly decorated sculpturally, their interior as well as their façades. The types of decorations found in the pagan period buildings are facing plates of white marble, columns and re-used Byzantine capitals. During the Christian period the cornices under the roofs of some churches were made out of limestone segments with denticles. The altar barrier of the Palace Church was made of marbles, decorated with the traditional geometrical and plant-like ornaments. A lion statue (from Roman times?) and a part of a relief of the Thracian heros was incorporated into the façade of the eastern gate.
Capital from the Large basilica
ZVaklinov, p. 176
Sculpture of a lion
ZAladzhov, p. 54
A stone plate with a groove
ZAladzhov, p. 24

The architecture of Pliska and Preslav is enriched by the diverse stone decoration – volumetric and in relief, with the specific proto-Bulgarian palmette.(V.K. Most of the examples are from Preslav).
NTjuleshkov, p. 54
The Proto-Bulgarian palmette with three or five leaves resting on two volutes, symbolyzing the Tree of Life, is a major artistic element in the architectural and applied arts. – Belt ends from Aq-alan (IX-X c.) near Constantinople
NTjuleshkov, p. 55