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ing walls, with steep stairways built between parallel walls recessed into the north
and south walls, holding a fill of carefully laid stone and mortar. The stone blocks—
mostly tonalite, with some granite—tend to be smaller, and basal stones can be the
same size or small than those in the rest of the wall. Most towers were built directly
over leveled bedrock, without a foundation, except Tower 13, which presents a large
foundation.
The ground plan of the towers varies from rectangular to rhomboidal (e.g. inner
angles at Tower 7: 73–109°). Their size (75–125 m
2
) and height (2–6 m) also vary
widely, with the northernmost towers being higher than the rest, apparently to compensate for the descent in the height of the hill in this end. The towers are regularly
spaced (4.7–5.1 m). Additionally, Towers 11 and 12 have an area greater than the
average; combined with the change in orientation, Tower 13 would be hidden to
some observers to the east. On each of the shorter walls (north and south), a flight
of stairs leads up to the summit. The northern stairways are usually centered along
this side, though not always aligned with the long axis of the tower. The southern
stairways, on the other hand, are often offset towards the east side. All the stairs are
narrow (1.4–1.5 m wide), and their height varies widely (1.3–5.2 m).
Tower 9 was excavated (Ghezzi, Alvarez, et al., 2013), determining the stairs
were built with stone blocks and slabs; each step is composed of several blocks
joined with mortar, and relatively larger blocks are found in the landing. Often the
blocks have two faces, so they form the treads, or part of the stair that was stepped
on, and the risers, or vertical portions between each tread. Usually a block laid on
the edge of a step is interlocked with the sidewalls. The steps in the northern stairway of Tower 9 have treads 0.24 m deep, and risers 0.24 m high, while those in the
southern stairway have 0.24 m deep treads and 0.18 m high risers. These dimensions would suggest that the northern stairs favored going up, while the southern
stairs favored going down (Hoskins & Milke, 2013). However, the stairways, which
are less steep than those in the Fortified Temple, were not meant for defense, and
such differences in the heights of the risers may be related to the direction of ritual
ascent and descent from the towers, as suggested by Malville (2011). Likewise, the
importance of the concept of duality has been documented in the Andes, and its
manifestation in these dual stairs, as well as in those in the entrance plaza to the
Administrative Centre and the atrium of the Temple of the Pillars, the observation
of both the sunrise and the sunset at the Thirteen Towers, and the use of the doublestep motif in the slitted pillars of the temple and in sculptural pottery vessels found
at Chankillo, reflect the symbolic importance of the dual stairs of the Thirteen
Towers (Ghezzi, 2016). Some tower summit floors have been partially preserved.
They consist of a layer of coarse sand, which may have been covered with mud. The
existence of the stairs strongly suggests that the summits were important loci of
ritual activity related to the solar cult.
The Chankillo Solar Observatory and Ceremonial Centre: A Heritage for the World
ing walls, with steep stairways built between parallel walls recessed into the north
and south walls, holding a fill of carefully laid stone and mortar. The stone blocks—
mostly tonalite, with some granite—tend to be smaller, and basal stones can be the
same size or small than those in the rest of the wall. Most towers were built directly
over leveled bedrock, without a foundation, except Tower 13, which presents a large
foundation.
The ground plan of the towers varies from rectangular to rhomboidal (e.g. inner
angles at Tower 7: 73–109°). Their size (75–125 m
2
) and height (2–6 m) also vary
widely, with the northernmost towers being higher than the rest, apparently to compensate for the descent in the height of the hill in this end. The towers are regularly
spaced (4.7–5.1 m). Additionally, Towers 11 and 12 have an area greater than the
average; combined with the change in orientation, Tower 13 would be hidden to
some observers to the east. On each of the shorter walls (north and south), a flight
of stairs leads up to the summit. The northern stairways are usually centered along
this side, though not always aligned with the long axis of the tower. The southern
stairways, on the other hand, are often offset towards the east side. All the stairs are
narrow (1.4–1.5 m wide), and their height varies widely (1.3–5.2 m).
Tower 9 was excavated (Ghezzi, Alvarez, et al., 2013), determining the stairs
were built with stone blocks and slabs; each step is composed of several blocks
joined with mortar, and relatively larger blocks are found in the landing. Often the
blocks have two faces, so they form the treads, or part of the stair that was stepped
on, and the risers, or vertical portions between each tread. Usually a block laid on
the edge of a step is interlocked with the sidewalls. The steps in the northern stairway of Tower 9 have treads 0.24 m deep, and risers 0.24 m high, while those in the
southern stairway have 0.24 m deep treads and 0.18 m high risers. These dimensions would suggest that the northern stairs favored going up, while the southern
stairs favored going down (Hoskins & Milke, 2013). However, the stairways, which
are less steep than those in the Fortified Temple, were not meant for defense, and
such differences in the heights of the risers may be related to the direction of ritual
ascent and descent from the towers, as suggested by Malville (2011). Likewise, the
importance of the concept of duality has been documented in the Andes, and its
manifestation in these dual stairs, as well as in those in the entrance plaza to the
Administrative Centre and the atrium of the Temple of the Pillars, the observation
of both the sunrise and the sunset at the Thirteen Towers, and the use of the doublestep motif in the slitted pillars of the temple and in sculptural pottery vessels found
at Chankillo, reflect the symbolic importance of the dual stairs of the Thirteen
Towers (Ghezzi, 2016). Some tower summit floors have been partially preserved.
They consist of a layer of coarse sand, which may have been covered with mud. The
existence of the stairs strongly suggests that the summits were important loci of
ritual activity related to the solar cult.
The Chankillo Solar Observatory and Ceremonial Centre: A Heritage for the World