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The journey from Delhi to Mathura is only two and a half hours along Yamuna Expressway. You can go to Mathura from Delhi by your own car, bus, or train. Train can also be a good option, which runs from New Delhi and Hazrat Nizamuddin in just two hours. There are many temples to visit in Braj, but if you want to visit the major sites of Mathura, Gokul, Vrindavan, Barsana, Nandgaon, Govardhan, etc. in your four days holiday, that is also a possibility.
You can visit Shri Krishna Janmabhoomi located in Mathura in the morning on the first day of your journey. There is also Dwarkadhish temple at a distance of one kilometer. You can visit major sites in Mathura in three to four hours.
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After this, you can get time to rest in the afternoon, as temples remain closed from 12:00 to 4:00 in Mathura Vrindavan. After 4 pm, you can visit Gokul, Krishna's childhood village, located just 12 km from Mathura, and visit all the major sites of Gokul till 8 pm.
On the second day, you can go to Vrindavan from Mathura and spend the whole day in the major temples and streets of Vrindavan. You can go to Old Vrindavan in the morning, where there are places like Shri Banke Bihari Temple, Nidhivan, Radha Vallabh Radha Raman, Yamuna Ghat, Chir Ghat, etc. Then, in the evening you can go to Vrindavan and visit the world-famous Prem Mandir, ISKCON Temple, etc.
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On the third day, you can visit Barsana, the village of Shri Radha Rani. In Barsana, you can visit famous places like Radha Rani Temple, Kusum Sarovar, Kirti Mandir, etc., and till afternoon you can visit all the major places here. You can rest there in the afternoon. After that, you can go to Nandgaon, the village of Shri Krishna, where Nand Baba Temple, Mahadev Temple, etc. are situated.
On the last day of your trip, you can go to Govardhan and take a 7 kos circumambulation of the Govardhan mountain located here. You can do the parikrama on foot or by e-rickshaw. Also, you can also visit Radha Kund located in Govardhan, and after visiting the beautiful places here till evening, you can leave for Delhi.