INVESTIGATIONS ALONG THE WESTERN AQUEDUCT OF NICOPOLIS AD ISTRUM (Ivan Tsarov – tsarov@abv.bg) The Dichin-West Site. The specus known from 2003 was investigated in two new areas - A and L. The aim was to clarify the existence of two duplicated terracotta pipelines. Fragments of terracotta pipes, two of them connected by a socket, were found in area A. The pipes were dismantled and only some terracotta fragments were left on the site. Later, some time after dismantling, the ditch was gradually filled with debris from the destroyed pipelines. The existence of a ledge testifies that the specus rose above the surrounding terrain in antiquity. Because of the erosion of the riverbank, the place where the arches joined the specus has been destroyed, and the beginning of the pipes is missing. Part of the southern side of the specus was excavated in area L. The Rositsa River Site. In 2003, five piers from the arches of the aqueduct were discovered within the riverbed. In 2004, Pier No. 5 (3.65 by 3.05 m), partly lying on the riverbank, was excavated. The other piers lie in the river, almost entirely covered by river deposits. It was possible to measure only Pier No. 4 (3.8 by 2.8 m). Piers Nos. 4 and 5 are not aligned and obviously, the arches of the aqueduct made a turn of 34 degrees there. In antiquity, the channel, currently silted up, was the main riverbed. Piers constructed of monumental limestone blocks were built within the ancient riverbed and alongside it. As far as Piers Nos. 1 – 5 are concerned, in antiquity they were built on dry land. A fragment of a stone channel, identical to others known from different parts of the aqueduct, was found close to Pier No. 5.

THE WESTERN AQUEDUCT OF NICOPOLIS AD ISTRUM (Ivan Tsarov – tsarov@abv.bg) A sector of the water-conduit (specus) of the main western aqueduct of Nicopolis ad Istrum was discovered on the border between the lands of Village of Resen and Village of Nikyup. It was traced out at 182 m in length. A sondage was carried out. The water-conduit of the aqueduct was built inside a trench. Part of its vault was destroyed. The vault was constructed of stones bonded with mortar and was 28 – 30 cm thick. A shuttering was used in its construction. The walls of the aqueduct were built of stone slabs bonded with mortar and its bottom had a trapezoidal cross-section. Traces from limescale were documented up to 20 cm above the bottom.

NICOPOLIS AD ISTRUM. CASTELLUM AQUAE (Ivan Tsarov – tsarov@abv.bg) The remains of _castellum_ _aquae_ of the western aquaeduct were situated on the highest place in the western extra muros quarter of Nicopolis ad Istrum. The eastern and the western walls of _castellum_ _aquae_ were 12.60 m long and the northern and southern walls were 12.50 m long. The southern wall was preserved up to 5.10 m in height. Part of a barrel-vaulted ceiling covering the reservoir was documented. The faces of the wall were constructed of small ashlars of sandstone in opus incertum. The emplectum consisted of uneven stones bonded with mortar and with courses of bricks. There was an outfall for emptying the reservoir in the southern wall. A second outfall for emptying the reservoir with a canal-lock was documented in the western wall of _castellum_ _aquae_. Its bottom was paved with limestone ashlars connected with clamps. There was an inscription with a red-brown paint on one ashlar that reads: ΔЄΙΑ. The ashlars were arranged over a layer of mortar which covered courses of bricks built over a foundation of uneven stones bonded with mortar. A water-conduit of terracotta-pipes, dated by three coins of AD 325 – 350, was discovered close to the eastern wall of _castellum_ _aquae_. During Period I, _castellum_ _aquae_ was used as _complex_ _divisorium_. The presence of distributors and canal-locks indicated of direct water outfall without keeping and accumulating the water. During Period II, _castellum_ _aquae_ was constructed to serve as a water reservoir. Its approximate inner size was 10.80 m by 8.60 m by 4.50 m and thus, its capacity was c. 400 cbm.

NICOPOLIS AD ISTRUM. CASTELLUM AQUAE (Ivan Tsarov – tsarov@abv.bg) The explorations of _castellum aquae_ continued. The structure was 12.60 m by 12.50 m in size. Its bottom was paved with limestone ashlars held together with clamps. Building inscriptions with red-brown paint were documented on some ashlars. One inscription says: ΔΕΙΑ. The ashlars were laid over two courses of bricks. Six courses of uneven stones bonded with mortar were situated below the bricks. Nine rectangular barrel-vaulted chambers, built of bricks and stones bonded with mortar, were constructed under the courses of uneven stones bonded with mortar, at the lowest part of _castellum aquae_. The southeastern chamber was 3 m by 2.40 m in size and 1.56 m in height. One of the western chambers was 2.98 m by 2.42 m in size and 1.55 m in height. The chambers had structural function and were not accessible from the outside. A third water-conduit of terracotta pipes was discovered to the east of the cistern. An earlier midden pit of the 4th century AD, cut during the construction of the structure, was documented. The stratum related to the functioning of _castellum aquae_ contained coins of AD 325 – 350. This is _terminus post quem_ for the construction of the cistern, while _terminus ante quem_ was AD 400 – 425. The previous hypothesis that _castellum aquae_ was built in the 2nd century AD and later it was reconstructed is now rejected.

NICOPOLIS AD ISTRUM. CASTELLUM AQUAE (Ivan Tsarov – tsarov@abv.bg) The explorations of _castellum aquae_ continued. It was found that a structure of the reservoir shown on the aquarelle painted by Felix Philipp Kanitz in 1871 is an artistic interpretation. The inscriptions documented on six ashlars of the bottom of the reservoir were conserved. The inscriptions were written with brown paint and probably indicated the position of the relevant ashlar within the structure. A sector of a water-conduit consisting of 24 terracotta pipes was discovered along the northern wall of the reservoir. The pipes were 30 – 35 cm in diameter and 42 – 49 cm long. The water-conduit was constructed in a hurry. The security guard for the aqueduct 22.5 km long was abandoned during the 4th century AD.

NICOPOLIS AD ISTRUM. CASTELLUM AQUAE (Ivan Tsarov – tsarov@abv.bg) A fourth terracotta water-conduit was discovered to the east of _castellum aquae_ and the parallel one was thoroughly explored. Two of the pipes of the southern water-conduit had _spiramina_ that were closed with terracotta stoppers plastered with maltha. A building destroyed by a fire was discovered close to the northeastern corner of the cistern. Its walls were 56 – 60 cm wide, built of ashlars bonded with mud. The explorations of the terracotta water-conduit continued from the northern side of the cistern and a section, 15.80 m long, was discovered. A _fovea reversoria_ was discovered close to the northeastern corner of the cistern.

NICOPOLIS AD ISTRUM. CASTELLUM AQUAE (Ivan Tsarov – tsarov@abv.bg) The lead pipes from the water-conduit system of the _castellum aquae_ were looted during the Ottoman and the Early Modern periods. Four water-conduits of terracotta pipes were discovered. They were constructed after AD 325 – 350, when the aqueduct was already in exploitation for more than two centuries and its technical condition was bad. Some of the terracotta pipes had _spiramenes_ closed with circular terracotta caps. The two buildings situated to the north and to the south of the water-conduits were partly excavated. A layer of fragmented tegulae and imbrices from the collapsed roof was discovered in the southern building.

NICOPOLIS AD ISTRUM. CAPUT AQUAE (Kalin Chakarov – kalinsbicke@abv.bg) The catchment of the western aqueduct of Nicopolis ad Istrum was explored in front of the entrance of the Musinska Peshtera Karst Cave. The catchment was constructed of 32 ashlars arranged in four courses, each one consisting of eight ashlars. There were П-like iron clamps, now missing, that held together the ashlars of the first and the second course. The inner size of the catchment was 4.23 m by 4.65 m and it was 2.20 – 2.40 m deep. There were two openings on its wall, the lower one connected to the main water-conduit of the aqueduct. The construction of _caput aquae_ of the western aqueduct of Nicopolis ad Istrum could be dated to the reign of Hadrian. The temperature of the water from the Karst spring was 13.9°–14.1°С and during the explorations its capacity was c. 50 liters per second. A survey was carried out along the sections of the aqueduct located near the Villages of Musina, Dichin and Vodolei.