Istanbul (Turkey)

Free to read here, from Project Gutenberg.

Byzantine Constantinople, the walls of the city and adjoining historical sites

Alexander Van Millingen

The Destruction of the Greek Empire and the Story of the Capture of Constantinople by the Turks

Edwin Pears

Journal of a Visit to Constantinople and Some of the Greek Islands in the Spring and Summer of 1833

John Auldjo

Of the Buildings of Justinian

Procopius

Narrative of Travels in Europe, Asia, and Africa, in the Seventeenth Century, Vol. I

Evliya Çelebi

Constantinople, v. 1 (of 2)

Edmondo De Amicis

Constantinople: The Story of the Old Capital of the Empire

William Holden Hutton

Constantinople, painted by Warwick Goble, described by Alexander Van Millingen

Alexander Van Millingen

Constantinople

Théophile Gautier

French

Memoirs or Chronicle of the Fourth Crusade and the Conquest of Constantinople

Geoffroi de Villehardouin

The Walls of Constantinople

B. Granville Baker

The Prince of India; Or, Why Constantinople Fell — Volume 01

Lew Wallace, also an audiobook

Constantinople and the Scenery of the Seven Churches of Asia Minor

R. Walsh

Narrative of Travels in Europe, Asia, and Africa, in the Seventeenth Century, Vol. II

Evliya Çelebi

The Wanderer's Necklace

H. Rider Haggard, also an audiobook

The Antiquities of Constantinople

Pierre Gilles

Constantinople, v. 2 (of 2)

Edmondo De Amicis

Speaking of the Turks

K. Ziya Mufti-zada, bey

The Captain of the Janizaries

James M. Ludlow

The Near East: Dalmatia, Greece and Constantinople

Robert Hichens

Oriente

Vicente Blasco Ibáñez

Spanish

Constantinople old and new

H. G. Dwight

The Prince of India; Or, Why Constantinople Fell — Volume 02

Lew Wallace

L'homme qui assassina: Roman

Claude Farrère

French

Viaggio a Costantinopoli (1609-1621)

Tommaso Alberti

Italian

De Pontoise à Stamboul

Edmond About

French

Constantinople de Byzance à  Stamboul.

Celâl Esad Arseven

French

Aziyadé

Pierre Loti

French

Konstantinopel en het Serail

Anonymous

Dutch

Fantôme d'Orient

Pierre Loti

French

Spears of destiny

Arthur D. Howden Smith

Aasian tytär

Pierre Loti

Finnish

Konstantinopelin valloitus

W. O. von Horn

Finnish

The beauties of the Bosphorus

Miss Pardoe