turrets. Mavrodinov likens the narthex of the Round Church to similar structures in the churches of Mount Athos, because of its depth. Together with the north and south wall, the entrance of the narthex effectively isolates two smaller parts of the atrium, similar in plan and accessible through doors. The north part includes a small necropolis, while the south part was probably a baptistery, as it features a square installation with a clay pipe that resembles a baptismal font. However, Nikolova considers its shape much too unusual and its depth unsuitable for baptism, and believes it may instead have been designed as a vessel for dispensing holy water. Measuring , the narthex is the part of the Round Church which has survived in best shape, as some of its walls reach . Its two turrets have a diameter of ; each has an entrance facing the interior of the narthex and three windows. The higher reaches of the towers were reached via spiral stairways, archaeological remains of which have been unearthed in the north turret. There are two pairs of columns inside the narthex, supporting its second floor, which is accessible from the north tower. The columns divide the narthex into three naves and mark the way from the narthex entrance to the gates of the rotunda. Rotunda The round cella is the easternmost and most important part of the church, as it was where the liturgy was performed. The diameter of the rotunda is . It is accessed through three gates, all from the narthex. It was entirely covered by a dome. Twelve vaults, semicircular as seen from the inside and pentagonal on the outer wall, were constructed north and south of the rotunda's eastern part, the apse, which itself fits into one of the vaults. Large buttresses reinforce the structure both inside and outside. A circle of ten or twelve white marble columns was inscribed inside the rotunda, from the interior buttresses. The capitals of the columns are similar to those of the royal palace in Preslav. A copper-plated wooden coffin lay in a burial chamber by one of the vaults near the apse. The semicircular apse fits naturally with the other vaults of the rotunda despite being larger, and features vaults on its north and south walls. The marble ambon was situated in the center of the circle of columns and of the whole rotunda, directly under