Restoration of Keçiova Mosque, Algeria (2014-2018)

1. Historical Background and General Description

Origins and the Ottoman Period

The Ketchaoua Mosque is located in the historic Casbah district of Algiers, the capital of Algeria, and is one of the most significant surviving monuments from the Ottoman period. An engraving published in Civitates Orbis Terrarum by Braun and Hogenberg in 1575—most likely drawn by Antonio Salamanca around 1541—clearly depicts a domed mosque with a cylindrical minaret featuring a single balcony, built in the first half of the 16th century within the courtyard of an Ottoman palace. This palace was situated at the site of today’s mosque, then identified as Piazza del Re (Government Square), and surrounded by examples of Ottoman-era civil architecture and historic residences.

This structure, considered the earliest Ottoman building in the city, has been claimed to be the mosque commissioned by Barbaros Hayreddin Pasha in 926 AH / 1520 AD, of which only the inscription has survived to the present day. In one of two known 16th-century engravings, the mosque appears without a minaret; in the other, it is depicted with a cylindrical, single-balcony minaret and a single-domed cylindrical or polygonal mass. This form is consistently shown in engravings from the 17th and 18th centuries as well.

At present, two marble plaques—one in Arabic and the other in French—located at the three-bay last congregation portico at the southern entrance of the mosque, state that the building was constructed in 1021 AH / 1612–13 AD as Sebil’ul-Hayrat for followers of the Hanafi school of Islam.

A marble inscription written in Arabic, currently preserved in the Algiers Museum of Antiquities, records that the mosque was rebuilt and enlarged by Hasan Pasha, the Dey of Algiers, in 1209 AH / 1794–95 AD. The expanded form of the mosque commissioned by Hasan Pasha is clearly visible in several engravings from the first half of the 19th century.

Transformation During the French Period

Following the French occupation beginning in 1832, the mosque was forcibly confiscated and dismantled, then converted into the Catholic Saint Philippe Cathedral. During this transformation, large portions of the original structure were demolished, new church elements were added, and the mosque’s Islamic architectural character was significantly altered. The cathedral, redesigned as a model of the so-called Neo-Moorish Architecture, was reopened for worship in 1908.

Post-Independence Period

After Algeria gained independence in 1962, the building was returned to its original function as a mosque. The first Friday prayer after independence was held here, and the Ketchaoua Mosque became a powerful symbol of national independence.

Architectural Features

Style and Influences

Due to successive interventions over different historical periods, the architectural character of the Ketchaoua Mosque is multilayered:

• Ottoman–Moorish Architecture: A synthesis of Ottoman architectural principles and North African Moorish ornamentation.

• Byzantine Influences: Certain Byzantine traces are visible, particularly in the entrance and façade compositions.

• Hybrid Architectural Identity: The conversion of the mosque into a church and later reconversion into a mosque resulted in a departure from a classical mosque layout, creating a unique synthesis of architectural motifs.

Key Architectural Elements

• Entrance: A portico accessed by a staircase of 23 steps, supported by four black-veined marble columns.

• Minarets: Two octagonal minarets dominate the main façade.

• Interior: Galleries formed by white marble columns, striking Moorish-style plasterwork, and domed spaces.

• Tomb: The interior contains the grave of a missionary named San Geronimo, a remnant of the French period.

Repair and Restoration History

Early Interventions

The mosque suffered damage during the 2003 earthquake and was temporarily closed.

2009 Restoration Works

Around 2008–2009, the Algerian Directorate of Cultural Heritage initiated restoration works on critical areas, including the minarets, the central dome of the façade, and interior staircases. These interventions were carried out as part of a broader Casbah Restoration Program.

2013 Agreement and the TİKA Project

In 2013, a bilateral cooperation protocol was signed between Turkey and Algeria for the restoration of historical monuments. Within this framework, the restoration of the Ketchaoua Mosque was officially approved.

Major Restoration (2014–2018)

Restoration works began in 2014 and lasted approximately three years.
The project was implemented by the Turkish Cooperation and Coordination Agency (TİKA), with architects, archaeologists, and engineers from both Algeria and Turkey working collaboratively.

Main Objectives and Interventions:

• Removal of church elements from the French period (altar, bema, etc.)

• Faithful restoration based on the original Ottoman architectural layout

• Structural strengthening of the minarets, façades, and main dome

• Renewal of original calligraphy, ornamentation, and marble works in the interior

• Reorganization of flooring, construction of new staircases, and renewal of carpets and interior decoration

Reopening in 2018

Following the completion of restoration works, the mosque was officially reopened between 9–13 April 2018 and resumed worship with the Friday prayer.
This restoration holds great cultural significance, both because the mosque is a symbol of Algerian independence and because it is located within the UNESCO World Heritage Site of the Casbah of Algiers.

Significance of the Interventions and Conservation Philosophy

Protection of Cultural Heritage

The restoration was conducted not merely as the repair of a place of worship, but as a comprehensive effort to preserve historical identity and architectural heritage.

Architectural Authenticity

Ottoman-period architectural identity was taken as the primary reference, while French-period additions were distinguished and, where possible, removed.

Collaborative Approach

The project involved technical teams from both Algeria and Turkey, and was reportedly closely monitored by UNESCO experts.

Importance and Current Status

The Ketchaoua Mosque is one of Algeria’s most important cultural and historical symbols and is regarded as a rare and outstanding example of Ottoman architecture in North Africa.
Today, it is open both for worship and for visitors, and remains one of the most prominent landmarks of the Casbah.

Ketchaoua Mosque (Algiers) – Technical Restoration and Intervention Analysis

Pre-Restoration Condition Assessment

Structural Problems

Following the 2003 Boumerdès Earthquake:

• Vertical cracks in the minarets

• Tensile cracks at the dome drum

• Shear cracks in load-bearing arches

Due to French-period interventions:

• Disruption of the original load-transfer system

• Structural instability caused by heavy church additions

Material Deterioration

• Salt crystallization, particularly in lower wall sections

• Moisture-related deterioration:

  • Plaster blistering

  • Stone surface disintegration

• Marble columns:

  • Surface erosion

  • Mechanical wear and biological soiling

Historical Stratification Issue

The building embodies multiple historical phases:

• Ottoman mosque

• French cathedral

• Reconverted mosque

This created a conservation dilemma between preserving the documentary value of French-period elements and restoring Ottoman authenticity.

2. Restoration Approach and Conservation Principles

The restoration process was carried out in accordance with international conservation standards:

• Venice Charter (1964)

• Nara Document on Authenticity (1994)

• UNESCO Casbah Management Plan

Adopted Core Principles:

• Minimum intervention

• Reversibility

• Documentation-based restoration

• Restitution with reference to the Ottoman period

3. Structural (Static) Interventions

Minaret Strengthening

Internal Measures:

• Stainless steel core rods

• Injection grouts based on hydraulic lime

External Measures:

• Renewal of stone joints using traditional lime mortar

Objectives:

• Increasing seismic resistance

• Minimizing visual impact

Domes and Arches

• Crack injection at the dome drum

• Concealed steel tension systems

• Reinstallation of weakened stones in arches using original materials and techniques

4. Material and Surface Restoration

Stone and Marble Elements

Cleaning:

• Low-pressure micro-abrasion

• Non-chemical (non-ionic) methods

Consolidation:

• Ethyl silicate-based stone consolidants

Completion:

• Compatible yet distinguishable stone additions in line with restoration ethics

Plaster and Decorative Painting

• Removal of cement-based plasters from the French period

• Application of traditional lime, sand, and brick powder mixtures

• Reproduction of geometric and vegetal decorations with reference to the Ottoman period

• Controlled restitution rather than full reconstruction

Flooring and Drainage

• Installation of sub-floor moisture barrier drainage channels

• Use of natural stone flooring and carpet systems

Objective:

• Prevention of capillary moisture rise

5. Documentation and Monitoring

Throughout the restoration process:

• 3D laser scanning

• Photogrammetry

• Material analysis reports

Post-restoration:

• Recommendation of a periodic structural monitoring program