The Dal Pozzo chapel in the Camposanto houses two fragments of the True Cross. (Wikipedia)

"In the Chapel of the Reliquary (...) is a gold crucifix, dated 874, containing an alleged piece of the True Cross." (Wikipedia)

"A much larger piece of the True Cross was taken from the Basilica [of the Holy Cross in Jerusalem] on the instructions of Pope Urban VIII in 1629 to St. Peter's Basilica, where it is kept near the colossal statue of St. Empress Helena sculpted by Andrea Bolgi in 1639." (Wikipedia)

Scuola Grande di San Giovanni Evangelista: "In 1369, Philippe de Mezières (...) gave to the school a piece of the True Cross which it still owns to this day." (Wikipedia)

"Fragments of True Cross in the Serbian Orthodox Monastery of Visoki Decani" (Wikipedia) (Wikimedia)

The Basilica of the Holy Cross in Jerusalem or Basilica di Santa Croce in Gerusalemme holds "part of the Elogium or Titulus Crucis, i.e. the panel which was hung on Christ's Cross (...) and three small wooden pieces of the True Cross." (Wikipedia)

On May 22, 1533, Bishop François de Halluin placed in a gilded silver reliquary, pieces of the True Cross, relics from the Holy Sepulchre, the table of the Last Supper, Saint Honoré, the apostle Saint Thomas, Saint Acheul, and the dalmatic of Thomas Becket; this reliquary was placed at the top of the spire, below the iron cross. (Wikipedia)

The Imperial Cross, "kept in the Imperial Treasury in the Hofburg", "served as the container for (...) the reliquary of the True Cross in the lower shaft". (Wikipedia)

Relics of the True Cross in the church of Saint-Guilhem-le-Désert. (Nomination file, p. 6) The "A of Charlemagne" in the abbey of Sainte-Foy de Conques contains the titulus of the True Cross. (Wikipedia)

"The Monastery of Santo Toribio de Liébana (...) holds and venerates part of the Lignum Crucis discovered in Jerusalem by Saint Helena of Constantinople, which is claimed to be the largest piece held." (Wikipedia)

The treasury of the Notre-Dame de Paris exhibits the reliquary of a fragment of the Cross of Christ. (Wikipedia) (Wikimedia)

The Church of the Holy Sepulchre houses the Chapel of the Invention of the Holy Cross, "believed to be the place where the True Cross was found." (Wikipedia) "The Greek Orthodox church presents a small True Cross relic shown in the Greek Treasury within the Church of the Holy Sepulchre at the foot of Golgotha." (Wikipedia)

Koutloumousiou Monastery "houses a piece of the Holy Cross." (Wikipedia)

Bamberg Cathedral: "The name "Nagelkapelle" ("Nail chapel") refers to a nail said to come from the True Cross; this nail has been venerated at Bamberg since the 14th century." (Wikipedia)