The Kitáb-i-Aqdas - The Most Holy Book
Index term: Baghdád
n54.
The Lord hath ordained that those of you who are able shall make pilgrimage to the sacred House
Two sacred Houses are covered by this ordinance, the House of the Báb in Shí­ráz and the House of Bahá’u’lláh in Baghdád. Bahá’u’lláh has specified that pilgrimage to either of these two Houses fulfils the requirement of this passage (Q&A 25, 29). In two separate Tablets, known as Súriy-i-Hajj (Q&A 10), Bahá’u’lláh has prescribed specific rites for each of these pilgrimages. In this sense, the performance of a pilgrimage is more than simply visiting these two Houses.
After the passing of Bahá’u’lláh, ‘Abdu’l-Bahá designated the Shrine of Bahá’u’lláh at Bahjí­ as a place of pilgrimage. In a Tablet, He indicates that the “Most Holy Shrine, the Blessed House in Baghdád and the venerated House of the Báb in Shí­ráz” are “consecrated to pilgrimage”, and that it is “obligatory” to visit these places “if one can afford it and is able to do so, and if no obstacle stands in one’s way”. No rites have been prescribed for pilgrimage to the Most Holy Shrine.
n107.
first day of Ridván
This is a reference to the arrival of Bahá’u’lláh and His companions in the Nají­bí­yyih Garden outside the city of Baghdád, subsequently referred to by the Bahá’í­s as the Garden of Ridván. This event, which took place thirty-one days after Naw-Rúz, in April 1863, signalized the commencement of the period during which Bahá’u’lláh declared His Mission to His companions. In a Tablet, He refers to His Declaration as “the Day of supreme felicity” and He describes the Garden of Ridván as “the Spot from which He shed upon the whole of creation the splendours of His Name, the All-Merciful”. Bahá’u’lláh spent twelve days in this Garden prior to departing for Istanbul, the place to which He had been banished.
The Declaration of Bahá’u’lláh is celebrated annually by the twelve-day Ridván Festival, described by Shoghi Effendi as "the holiest and most significant of all Bahá’í­ festivals" (see notes 138 and 140).
n138.
All Feasts have attained their consummation in the two Most Great Festivals, and in the two other Festivals that fall on the twin days
This passage establishes four great festivals of the Bahá’í­ year. The two designated by Bahá’u’lláh as “the two Most Great Festivals” are, first, the Festival of Ridván, which commemorates Bahá’u’lláh’s Declaration of His Prophetic Mission in the Garden of Ridván in Baghdád during twelve days in April/May 1863 and is referred to by Him as “the King of Festivals” and, second, the Báb’s Declaration, which occurred in May 1844 in Shí­ráz. The first, ninth and twelfth days of the Festival of Ridván are Holy Days (Q&A 1), as is the day of the Declaration of the Báb.
The "two other Festivals" are the anniversaries of the births of Bahá’u’lláh and the Báb. In the Muslim lunar calendar these fall on consecutive days, the birth of Bahá’u’lláh on the second day of the month of Muharram 1233 A.H. (12 November 1817), and the birth of the Báb on the first day of the same month 1235 A.H. (20 October 1819), respectively. They are thus referred to as the "Twin Birthdays" and Bahá’u’lláh states that these two days are accounted as one in the sight of God (Q&A 2). He states that, should they fall within the month of fasting, the command to fast shall not apply on those days (Q&A 36). Given that the Bahá’í­ calendar (see notes 26 and 147) is a solar calendar, it remains for the Universal House of Justice to determine whether the Twin Holy Birthdays are to be celebrated on a solar or lunar basis.
n154.
Raise up and exalt the two Houses in the Twin Hallowed Spots, and the other sites wherein the throne of your Lord . . . hath been established.
Bahá’u’lláh identifies the “two Houses” as His House in Baghdád, designated by Him as the “Most Great House”, and the House of the Báb in Shí­ráz, both of which have been ordained by Him as sites of pilgrimage. (See Q&A 29, 32 and note 54.)
Shoghi Effendi explained that “the other sites wherein the throne of your Lord . . . hath been established” refers to those places where the Person of the Manifestation of God has resided. Bahá’u’lláh states that “the people of the areas where these are situated may choose to preserve either each house” wherein He resided, “or one of them” (Q&A 32). Bahá’í­ institutions have identified, documented, and where possible, acquired and restored a number of the historical sites associated with the Twin Manifestations.
q29.
 
Question: Again inquiry hath been made about the pilgrimage.
Answer: By pilgrimage to the sacred House, which is enjoined upon men, is intended both the Most Great House in Baghdád and the House of the Primal Point in Shí­ráz; pilgrimage to either of these Houses sufficeth. They may thus make pilgrimage to whichever lieth nearer to the place where they reside.