This leads us directly to the second source of Ekadasi celebrations, a more popular one at that. Vishnu was on a quest to slay this Demon called Mura. As the quest prolonged, Vishnu decided to spend a night in a cave. Privy this momentary lapse in Vishnu's defense, Mura attempted to enter the cave and slay Vishnu. However, a woman called Ekadasi (popularly known as Vishnu's female attribute) appeared and slayed Mura. Much pleased with the women's benevolence, Vishnu decided to name the Ekadasi day after the lady. From then on men have tried to fight the Rajasic and Tamasic temptations of food, sleep, etc on this day. This is done to develop self-control and purge the sins accumulated since the previous Ekadasi.
Thiruvarangam, or Srirangam as it is popularly called is a marvelous island near Trichy and its beauty and glory are cherished by people who have visited the place. On account of its huge size (155 acres), it is called as the "biggest functioning Hindu Temple in the world". It has Lord. Vishnu in the reclining posture (The kidanthaan of 4 poses associated with Vishnu shrines - kidanthaan, irunthan, ninraan, nadanthan). It is so important to the Tamil tradition that the term 'kovil' is assumed to be Srirangam unless it is prefixed with something else. This is where Kamban initiated his Ramayanam. Barring Madhurakavi, this is the only temple where all the Azhwars have sung hymns in praise of the presiding deity. Divya Prabhandams are recited in a very expressive fashion (Araiyar Sevai) in this temple. Srirangam has a long history with the Ekadasi that appears on the month of Margazhi. Maasanam Margasheershoham, is a quote attributed to the Para Vasudeva. It means "Among the months, I am Margashirisha". So month coinciding/ending with the star Maargasirisha, the Dhanur Maasa (or Maargazhi) is very special for Vishnu Bhaktas all over the world. The 30 days of this months is spent reciting the 30 verses of Andal. The Ekadasi day corresponding to this month is called Vaikunta Ekadasi and is the most special among all Ekadasis. It is a Sukla Paksha Ekadesi. Srirangam is the oldest, largest, and most important of all the Vishnu temples in the world. It is the leader among vaishnavite temples. It is the primary temple, which every Vishnu devotee seeks to visit. So the celebration of Vaikunta Ekadasi in Srirangam is as big as it gets. While most Vishnu temples in the Southern parts of India observe Vaikunta Ekadasi and attract large crowds, Srirangam in all its 'Vaikunta Ekadasi' glory is a special sight to behold. All the 155 acres and the thousand pillars of the temple assume a festive look on this day.
Pagal Pathu/Raa Pathu: Vaikunta Ekadasi is celebrated for 21 days in Srirangam. The First 10 days preceding Vaikunta Ekadasi is called Pagal Pathu. Then comes the important Vaikunta Ekadasi Day and then the 10 days following this day is called Raa Pathu. As the names suggest, Pagal pathu is when the festivities are done during the day. Raa pathu has festivities during the night. On the day of Vaikunta Ekadasi, the Lord is decorated grandly (it is a popular belief that once upon a time, the now famous 'Orloff' Russian Diamond adorned the Lord) and carried to the Parama Pada Vaasal, which is the northern gate of the temple. This is the 'Vaikunta Vaasal' and is only opened once a year - on this day. The crowd that comes to witness this event has to be seen to be believed. It is a common belief that the real Vaikunta vaasal in heaven (Heaven's doors) open on this day. Nam-Azhwar attained moksha today. It also a popular belief that people who die today are destined for moksha. At the end of the first 15 days of thiurpaavai, Andal would have woken up all her thozhi's. Tomorrow, on Dwadesi, she would request permission from Dwara-Balakars (Guardian's of Vishnu's door) to enter the lord's abode and visit him. ("Nayakanai nindra nandagopan'udaiya kovil kaapane, kodi thondrum thorana vaayil kaapane, manikathavam thaal thiravai")
The tradition: 1000 years ago Ramanuja, laid down the procedures that needed to be followed during this month. Almost all those rituals and traditions are followed in Srirangam to the minutest detail. If one visits Srirangam, one may also witness the 'Saathadha' Vaishnavas. These vaishnavites are people who do not wear sacred thread. Ramanuja, a revolutionary in his time, initiated women and non-Brahmins into important roles within the faith. They occupied important positions in matters concerning religion and spreading of the faith. He was very interested in religion spreading to the common man and not being a possession of the elitist classes and therefore aspired for a caste-free vaishnavism. Unfortunately, it only remained a dream in his immediate future. Apart from this one may get to see several dance processions by turban clad individuals ( in the backdrop of Azhwar songs), and Veena recitals by the successors of the women-religious-heads appointed by Ramanuja 1000 years ago(Hear-say - I have not personally seen this).