This church is the bulgarian most famous medieval monument of Veliko Tarnovo. It was built and painted in the reign of the Bulgarian Tsar Ivan Assen II in honor of his great victory at the Battle of Klokotnitsa of March 9, 1230 (the day of St. 40 Martyrs).It was built by the despot Epirus Theodore Comnenus in the S. XIII – XIV. This is the main church of the monastery of the Great Lavra.The church is composed of several parts – a rectangular basilica with six columns placed in two rows, three semicircular apses and a narrow porch in western and also an annex building that was built later and the Western side.It was severely damaged in the earthquake of 1327 and restored in the first half of the fourteenth century.In this church are preserved frescoes of Santa Isabel with the infant John Mlekopitatelnitsa (on entry) and Santa Ana Mlekopitatelnitsa (above the front porch of the church) in the remaining space on the west wall are separate pieces – a picture schedule four rows of May, August and November. These frescoes are probably of the second half of the fourteenth century.In the church of the Forty Martyrs are the most important ancient epigraphic monuments, such as Assen and the edge of the column on the Rodosto strength of Khan Krum.On May 18, 1888, was the wedding held between the Prime Minister of Bulgaria Stefan Stambolov of Polikseni and Costache Stancioff of Svishtov.On September 22, 1908, in the same church, Prince Ferdinand declared Bulgaria’s independence. In the church are buried the kings Kaloyan, Ivan Asen II, Michael Shishman, and Queens Mary and Irina Ana, St. Sava of Serbia, and many other members of the royal family and the Bulgarian aristocracy. It also contains the remains of Kaloyan taken 800 years after his death.The church was declared a National Antiquity (SG br.69/1927 a) and architectural monument of national importance (SG br.102/1964) in addition to artistic monument of national interest.The church was named Orthodox Church of the Forty Martyrs.