German leaders on Tuesday marked the 500th anniversary since the day Martin Luther is said to have nailed his theses challenging the Catholic Church to a church door, a starting point of the Reformation.

German Chancellor Angela Merkel and President Frank-Walter Steinmeier took part in a service in the famous Castle Church in Wittenberg, where Luther supposedly posted his 95 Theses on Oct. 31, 1517.

Thousands were participating in different church services throughout the day in the eastern German town. The city also celebrated the anniversary with a medieval-style street festival including arts and cultural events.

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German Chancellor Angela Merkel attends celebrations for the 500th anniversary of the Reformation in front of the grave of Martin Luther at the Castle Church in Wittenberg, Germany, Tuesday, Oct. 31, 2017. (AP)

In remembrance of the 500th anniversary, Reformation day is a public holiday in Germany this year.

As Protestantism spread following Luther's revolt against the Catholic Church, religious wars erupted, dividing western Christianity in a schism that resulted in hundreds of years of violence, persecution and discrimination.