Yeraltı Mosque (Underground Mosque)

History and Architecture:

Kurşunlu Mahzen Mansion and Underground Mosque have a rich history dating back to 711 AD.
Initially, a large tower called Kahr Kulesi was constructed by Abdülaziz’s son Ömer. Over time, the area evolved into the current Kurşunlu Mahzen, which was converted into a mosque.
The structure, originally known as Kastellion ton Galatau, was built during the reign of Emperor Tiberios II (578-582) to protect against Arab invasions and control the entrance of the Golden Horn. This fortress was also linked to the chain preventing access to the Golden Horn.
It was later confused with the Galata Tower but was distinctively known as Galatau. The name challenges the common belief that “Galata” is of Genoese origin.
The fortress played a crucial role during the Crusades and various sieges, including the Islamic army’s siege in 717 and the Crusaders in 1027.
After the Genoese were granted settlement rights in Galata in 1267, they demolished existing walls, turning the fortress into a small Byzantine garrison.
Post the conquest of Constantinople, the fortress remained untouched due to Galata’s peaceful surrender.

Evolution into a Mosque:

The structure suffered damage during an earthquake in the era of Sultan Bayezid II, as noted by Evliya Çelebi. By the 16th century, it ceased to appear in records.
The Kurşunlu Mahzen Mansion, an exquisite example of Turkish civil architecture, was a customs house built on the large tower of the fortress. Notable depictions include John Lewis’s 1836 engraving.
An interesting legend involves the sealing of a section of the basement with lead, following a military campaign in 714, hence the name Kurşunlu Mahzen (“Lead-Sealed Basement”).
Despite Sultan Murad IV’s plans, a mosque wasn’t built until later by Çorlulu Köse Mustafa Bâhir Paşa. The minaret, rebuilt by Sultan Mahmud I after an earthquake, has undergone several transformations.

Architectural Features:

The Underground Mosque today stands as a unique structure with its entrance at Kemeraltı Street level. It has a rectangular plan with multiple entrances.
Inside, 45 independent columns support the structure, with significant space between them, creating a distinctive spatial experience.
The mosque houses three platforms attributed to Eshaptan Amr B.Al-‘Aş Al-Sahmi, Vehb B. Huşeyre, and Süfyân B. Uyeyne, adding to its historical significance.

Cultural Importance:

The transformation of a 1500-year-old fortress into a mosque exemplifies Istanbul’s rich, multi-layered history and cultural adaptation.
The Underground Mosque stands out among Istanbul’s religious sites for its unique space and historical significance, tracing back to Byzantine times.

Visiting Tips:

When visiting, take time to appreciate the architecture and the layers of history evident in its walls.
The mosque’s interior is a marvel of historical architecture, offering a different perspective on Istanbul’s religious sites.
Be respectful of the religious practices and local customs when visiting.