Bangkok insights
All traveling needs before visit Thailand

Location
At Phanfa Leelad Bridge on Ratchadamnoen Klang Rd. Surrounds by Wat Ratchanadda and Wat Saket on the opposite side of Rop Krung Canal.
Access by car
Drive to Thanon ratchadamnoen Klang Rd. The fort is another small landmark of the road.
Access by bus
Plenty of buses that pass Ratchadamnoen Klang Rd pass the fort
Access by boat
Visitors from Sukhumvit, Petchburi, Central World, Siam can escape the road traffic by getting on the San Saeb boat to the end of route at Phanfa Leelad Bridge Pier. The fort is there.
Acceess from Wat Pho
Many people come to Wat Aroon after they visit Wat Pho. Just walk on the left path outside the wall. Walk to junction and then go straight ahead to Tha Tian Pier. Get on a ferry to the opposite bank where Wat Aroon is.
Admission fee
Daily open
Free admission, prohibited areas are the fort itself.
Tips :
1. City Hall serves free bicycles for travelers to get to sights.
2. City Hall also provides street cars that imitated shape of Bangkok tram in 1900's to run around Rattanakosin Island major sights. they leaves every 10 minutes and are free of charge.
Aerial view of Mahakan Fort, Bangkok from Google map