Kulashekhara Alwar explains us the last few days of Lord Rama in the below verse...
Seri tava chambuhan tannai Senru konru Sezhu maraiyon uyir meettu tavatton eenda
nirai mani poon aniyum kondu ilavanan tannai tambiyal vanettri munivan venda
tiral vilangum ilakkumanai pirindan tannai tillai nahar tiru chittirakoodam tannul
uraivanai maravada ullam tannai udaiyom mattru uru tuyar adaiyom anre
In Uttara Kandam, we can see events related to Lord Rama's last few days. Sage Agastya narrates various stories to Lord Rama. Later, Lord Rama ruled the kingdom in a very glorified manner. We have already seen the place in the footsteps of Lord Rama, where Rama performed the Ashvamedha Yaga, the sacrifice horse strayed into the forest, which was captured by Lava and Kusha. Unaware that the horse belonged to Rama and he was their father, they engaged in conflict and defeated Rama's army led by his brothers. Eventually, Rama himself came to battle his own sons. After Hanuman and Valmiki's intervention, Rama knows the truth and invites them to return to Ayodhya. Later they discussed on whom to declare as the next king and He did pattabhishekam for the son's of Bharathan and Lakshmanan, so that they can take care of the kingdom. Lord Ram ruled Ayodhya for 11000 years, which is stated by Sage Valmiki in the verse - "Dasha Varsha Sahasrani Dasha Varsha Shatani Cha" (Rama ruled the world for 10000 years and then 1000 years i.e. 10*1000 + 10*100 = 11,000 years). It was from here (Guptar Ghat) that Lord Sri Rama ruled the earth for 11000 years and left for Vaikuntam from here.
Gupt means secret or disappear. Here Sri Rama disappeared from this world. We don't find any information about the physical body of Lord Rama and Krishna during their departure from the earth and we don't find any information on rituals performed to it. Hence, they would have left along with their physical body. The region between Satya Loka and Sri Vaikuntam is known as Santhanika Loka. It is said that people in this Santhanika Loka can reach the next Sri Vaikuntam in short span. According to Alwar pasuram "anru sarasarangalai vaikunthatherri adal arava pakai eri asurar thammai venru....", Sri Rama took everything to Vaikuntam.
According to the verse in Tiruvaimozhi of Nammazhwar - Centum : 7-5
karpaar iraama piraanai allaal marrum karparO?
purpaa muthalaap pullerumpaathi onrinriye,
narpaal ayoththiyil vaazum charaacharam murravum
narpaalukku uyththanan naanmuka nnaar perra naattule
Sri Rama in His Avatar in this world, ruled for 11,000 years. Lord Rama is known as Moksha Pradhan (granter of mukthi). He despatched all moving and non-moving beings in Ayodhya to Vaikuntam. After His Avatar mission was over, He was to return to Sri Vaikuntam, the same was intimated by Kala Deva. Before that, Lakshmana who could not bear separation from Sri Rama, departed for Sri Vaikuntam from Lakshman Ghat, earlier. After some days, Sri Rama decided that His time for departure had come. With all His people, He came to this place, which is about 10 miles from Ayodhya. This place on Sarayu river banks, is called Goprachara Teertham or Guptar Ghat. Sri Rama left this place, in white dress and with darbha [a type of grass] in his hand. (Explained in 109th Sargam and how He left is explained in 110th Sargam) The parayanam of these two sargams was done in Guptar Ghat.
While departing from the earth, Lord Rama didn't leave his bhutha udal (body made of pancha bhuthams namely pruthvi, appu, thejas, vayu and akash). Below is the image of Lord Rama's idol at Guptar Ghat.
History of this place: We can see the wide flow of Sarayu river, who emerged from Brahma and who was brought here by Vasishta. From this place in Sarayu, Lakshmana, incarnation of Adisesha, departed for Vaikuntam. On the shore, we can see a temple for Lakshmana. Sri Rama, Sri Sita and Lakshmana are gracing. Sri Rama was dark blue, while Lakshmana was fair complexioned. One was personification of patience, while the other desired nothing except serving the Lord. One was incarnation of the Lord, while the other was incarnation of Adisesha. Sri Rama ruled the Kingdom for 11,000 years. When this period was about to end, Brahma and other Devas discussed and decided to remind Sri Rama that He should return to Vaikuntam; they also decided to depute Kala deva, to go to Sri Rama. Kala Deva pondered as separating Sri Rama from the people of Ayodhya was not that easy. Finally, he decided to carry out the mission, and in the guise of an elderly man, he reached Sri Rama's palace.
Sri Rama welcomed him and offered all respects, due to a guest. When Sri Rama asked the purpose of the old man's visit, the old man replied that he wanted to talk to Sri Rama confidentially, with none else present. When Sri Rama accepted, the old man said that even Lakshmana should not be present! That time only Sri Rama realized that He had never considered Lakshmana as separate from Him! Since the old man insisted on Lakshmana also leaving them, Sri Rama agreed. The old man put another condition that no one should interfere in their conversation and if anyone intruded that person should be killed by Sri Rama Himself! Sri Rama was surprised at these conditions; still, respecting the guest, He did not object and entered into private conversation with the old man.
Lakshman was guarding at the door, so that none entered the room. Kala Deva, in the guise of the old man, told Sri Rama that His time on Earth was getting over and that He should return to Vaikuntam. As they were conversing, sage Durvasa appeared at the door. Lakshman stopped Durvasa from entering and told about the order. Enraged, Durvasa said that if he was not allowed, he would curse all. Lakshmana was in a dilemma. Finally, Lakshmana decided that he would go inside and get Sri Rama's permission. Lakshmana entered and conveyed the arrival of Durvasa. But having violated the order, Lakshmana had to be killed by Sri Rama! The old man took leave and requested Sri Rama to keep up His promise and not to violate His own words! Sri Rama had to kill Lakshmana. Can this ever happen? Sri Rama could never sleep without Lakshmana. Considering Sri Rama's delicate position, He was advised that if Lakshmana got separated from Sri Rama, it was equal to killing Lakshmana! Accepting this, Lakshmana came to Lakshman Ghat and meditating on the Lord, he left for Vaikuntam. Unable to bear the separation of Lakshmana, Sri Rama also left for Vaikuntam, from this place, Guptar Ghat. The view of sunset from Guptar Ghat is breathtaking. A boat ride is a must while visiting this place.