Vaikunta Ekadashi January 11
Today is an important festival day for all Vaishnavites. this festival is observed on the 11th day of waxing moon in the Tamil month of Margazhi/Dhanu Malayalam
It is believed that the the inner most dwara ( doors) of the Vaikuntam ( Vishnu’s abode) gets opened on this day. In almost all Vishnu temples this happens to be the Northen gate which remains closed throughout the year and is thrown open just for a day for the devotees. Devotees throng the temple to pass through the gate.

This is also the day Nammazhvar, the great Vaishanavite saint reached Vaikunta and it is believed that Lord himself arrived at the Gate of the Vaikuntam to take him inside.
This Gate ( the gate to heaven, ) on Ekadashi  day gets opened at 4 AM in temples and God is taken through this gate in a palanquin followed by thousands of devotees. Many observe fast during this day, meditate and chant Lord’s name. Those who have faith firmly believe that they would attain moksha at feet of Lord.
These festivals are very famous in Srirangam, Tirupati and almost all 108 Tirupati temples of Vishnu. This is also known as swargavathil Ekadashi in Kerala.
Click this link to have a glimpse of this festival in Srirangam.