For a great day out make sure you visit Ancient Siam.
Ancient Siam (formerly known as Ancient City) is a park constructed under the patronage of Lek Viriaphant and spreading over 200 acres (0.81 km2) in the shape of Thailand.
The founder's original idea was to create a golf course with miniatures of Thailand's historically significant structures spread around the course. During his research he found most structures being severely damaged over time and decided instead of creating new miniatures to save the original structures when possible or re-creating them full size or scaled down.
Ancient Siam is dubbed as the world's largest outdoor museum. Situated close to the Crocodile Farm in Samut Prakan Province, the 320-hectare city features 116 structures of Thailand's famous monuments and architectural attractions. The grounds of Ancient Siam correspond roughly to the shape of the Kingdom, with each of the monuments lying at their correct places geographically. Some of the buildings are life-size replicas of existing or former sites, while others are scaled down.
The replicas were constructed with the assistance of experts from the National Museum to ensure historical accuracy. Outstanding works include the former Grand Palace of Ayutthaya (destroyed in the Burmese invasion of 1767), Phimai Sanctuary in Nakhon Ratchasima, and Wat Khao Phra Viharn on the Cambodian border.
Ayutthaya is an island at the confluence of three rivers: the Chao Phraya River, the Lopburi River and the Pa Sak River. As the train station is at the east side off the island, most visitors will need to cross the river by ferry boat. Navigating your way around the island is not particularly hard: U Thong Rd is a ring road that circumvents the island completely. Most temple ruins can be found at the northwest of the island, while accommodation and night life is clustered around the northeast. As non-Siamese peoples were not allowed to live inside the city walls, things foreign are found off the island.
Get to Ayutthaya: By car
From Bangkok, one can get to Ayutthaya by various routes:
- Take Highway 1 (Phahon Yothin) via Pratu Nam Phra In and turn into Hwy 32, then turn left to Hwy 309 to Ayutthaya.
- Take Hwy 304 (Chaeng Watthana) or Hwy 302 (Ngam Wong Wan), turn right into Hwy 306 (Tiwanon), cross Nonthaburi or Nuanchawi Bridge to Pathum Thani, continue on Hwy 3111 (Pathum Thani–Sam Khok–Sena) and turn right at Amphoe Sena into Hwy 3263 to Ayutthaya
- Take Hwy 306 (Bangkok–Nonthaburi–Pathum Thani), at Pathum Thani Bridge Intersection, turn into Hwy 347 and Hwy 3309 via Bang Sai Royal Folk Arts and Crafts Centre, Amphoe Bang Pa-in, to Ayutthaya.
- Take Expressway No.9 (Si Rat Expressway) via Nonthaburi–Pathum Thani and down to Hwt 1 via Bang Sai Royal Folk Arts and Crafts Centre, turn left onto Hwy 3469 towards Bang Pahan and turn right at Worachet Intersection to Ayutthaya.
The cheapest and most scenic way of reaching Ayutthaya is by train. It regularly departs from Bangkok’s Hualamphong Train Station and stops in Ayutthaya. The trip takes about 2 - 2.5 hrs depending on the type of service. Second-class seats (A/C) cost 245 baht, third-class is just 15 baht (!) (no reservations and seats are not guaranteed). Although in the past railway employees preferred not to sell 3rd-class tickets to foreigners, as of 2011 the employees were explicitly offering 3rd-class seats to western tourists as a standard option. Also note that some train stations (for instance Bang Khen) do not appear on the sites map, and that tickets may even be cheaper. If you have local friends, they may have some good advice.
The railway station is not on the island but across the river a short ferry ride away. Walk across the main road and down the small street straight ahead. Ferry boats run every few minutes and cost 4 baht.
Buses operate every 20 minutes or so from Bangkok's Northern Bus Terminal (Moh Chit) directly to Ayutthaya (despite what locals say, the last bus leaves at 18:00). First-class air-con buses charge 56 baht. This trip is scheduled to be around an hour and a half, but allow at least two hours for the trip since the buses stop rather frequently and there are often jams on the roads out of into Bangkok.
- To get to the Northern Bus Terminal, go to Mo Chit BTS Station. Upon exiting the gate, cross the bridge on the right to go to the bus stop, and take bus service 3 or bus service 77. (air-con buses charge 12 baht, non air-con buses charge 7 baht.) Bus ride is about 10-15 minutes and the Northern Bus Terminal destination is the last stop for the bus services. However, buses do not stop in the Northern Bus Terminal, but at the bus stop across the street. Cross the bridge to get to the bus terminal.
- Bus service 3 runs also near Khao San. It goes by Chakrabongse Rd which is a street on the western end of Khao San. The trip to the Northern Bus Terminal from here takes around 1 hour. Getting back in the evening can take longer due to traffic. Official metered taxi directly from Mo Chit bus terminal taxi stand to Khao San Road costs 105 baht.
Also you can take a minivan from the Victory Monument direct to Ayutthaya. Takes 1 hour and costs 100 baht. Minivans depart every 20 minutes or so.
The buses run from 04:30–19:15. For more details, call Tel. +66 29 362 852-66 or see the website  and Ayutthaya Bus Terminal, Tel. +66 35 335 304.In Ayutthaya, the central BKS bus station is on the south side of Naresuan Rd next to the Chao Phrom Market. songthaews to Bang Pa-In also leave from here. Some 1st-class buses to Bangkok, however, leave from the north side of the road some 500 m to the west, on the other side of the khlong (canal); the queue for air-con buses is easy to spot.
From Kanchanaburi, take a local bus of horrible quality from the main bus station to Suphanburi for 50 baht (2.5 hours + long waiting for bus and departing) and then official airconditioned "minibus" (actually Toyota Hilux minivan) nr. 703 to Ayutthaya for 80 baht (1 hour). Big bus from Suphanburi to Ayutthaya was cancelled and replaced by minivan service nr. 703 even according timetable on bus station, although there is no price mentioned on timetable so 80 baht is probably farang (foreigner) price and locals pay less (they use this minivan service too). The best advice is avoid this route completely, because it will cost you 130 baht and you will tired after spending 4.5-5 hours (incl. waiting) to get from Kanchanaburi to Ayuthaya, so it's actually faster go back to Bangkok and get to Ayuthaya from Bangkok without any cheating or double prices and more comfortable for same amount of time or even faster and only little bit more expensive. A taxi from Kanchanaburi costs 2,000-2,500 baht (2 hours).
There is also a central bus station east of town serving northern destinations. It can be reached by songthaew. Ask around to find the appropriate stop.
By minibus (van)
Convenient minibus service (can get stuck in traffic, but makes no stops like regular buses) operates from the Victory Monument square in Bangkok. Take BTS Skytrain to the Victory Monument station, and go right on the elevated walkway. Stay on it until you cross a large road, then descend. The buses are parked at the side of the main traffic circle. The cost is 60 baht, takes around 1 hour to 1 hour 20 min. It's quite convenient since you don't have to go to bus terminals (nearby Mo Chit) but the only problem is that the minibuses don't have much space to carry big bags and have to wait until the car is fully filled.
Minibuses (van) from Kanchanaburi can be arranged by guest houses or any tour operators for around 400 baht. Most tour operators charge 400 baht for the 2.5 hours drive. There is one tour operator charging 380 Bbht, but this one is not recommended since it takes 5 hours to reach Ayutthaya. This one passes through Bangkok first.
Cruise boats run up the river from Bangkok, often stopping at Ko Kret and Bang Pa-In along the way. You'll need to book in advance as there are no scheduled services, just trips for tourists. It's a fairly lengthy trip (at least one whole day) and some of the larger boats offer (pricy) overnight tours.Travelling by boat to Phra Nakhon Si Ayutthaya is popular among foreigners since it does not only reveal the beauty as well as lifestyle of the people on both sides of the Chao Phraya River, but also reflects the life in history at the time of the Ayutthaya Kingdom when the Chao Phraya River served as a channel of transportation in trading with foreign countries.
Get around By bicycle
Bicycling around the ruins is the most enjoyable and fun way to spend the day. The archaeological park is easily reachable and manageable on bike even if you aren't very fit. The paths are paved and the distances between temples are small.
You can rent a bicycle for around 40 baht per day.
The bicycles are not necessarily well maintained, so be sure that they work properly (wheels are firm and inflated, seats adjusted to your height and well attached, handlebars don't slip); good shops will give you a free bike lock as well. There is a good bike shop directly opposite the train station.
Free map of the city is widely available in all hotels.
The park opens at 07:30. It is recommended that you begin your tour early, before the tour groups arrive from Bangkok. Take a big bottle of water with you.
Bicycle rentals: Soi 2 (where the majority of tourist hotels and restaurants are located) have numerous bike rental facilities. They are all next to each other so it will be easy to shop around and find the one with the best bike for you.
At T.W.T (TourWithThai) (before Tony's guest house which not far from minibus stop at Soi 2) has bicycles big and small size and seat for small child for rent. If you short of time maybe you can go around by motorcycle which you can rent in the same area.
Alternatively, you can get around town by tuk-tuk (motorized 3-wheeler). Ayutthaya's tuk-tuks are larger than the Bangkok variety and you can easily squeeze six people in on facing benches. Only "official" tuk-tuk drivers or tourist "helpers" can pick up passengers from the train station. You can verify their status by looking for their photos/name on a "Tourist Officials" board displayed at the southern end of the platform. These people are required to charge/work for fixed charges, usually quoting 300 baht/hour, but this can usually be bargained to a slightly lower price (e.g., 1,000 baht for 4 hrs).
You can also flag down tuk-tuks from the street and try to hire them, most drivers carry with them a stack of postcards featuring the famous sites of the city to ease communication, they also are used to the standard temple hopping circuit. If you have a map you can point out any of the destinations that you wish to see and they'll often quote a trip price and will wait for you at each stop. 200 baht per hour seems to be the starting point for tourist tuk-tuks picking up backpackers away from the station, although it can be possible to negotiate a lower price.
From Ayutthya, mini-buses can be taken from the railway station into the city. Hiring a mini- bus within Ayutthaya costs between 400-500 baht/day. For travelling between Ayutthaya and Bang Pa-in, mini-buses regularly leave Chao Prom Market, Chao Prom Road starting from 06:00.
Boat trips to enjoy the beautiful scenery and Thai lifestyle along the Chao Phraya River, the Pa Sak River and around the town island of Phra Nakhon Si Ayutthaya are available. A long-tailed boat can be chartered at the pier in front of Chanthara Kasem National Museum, Pom Phet Pier, and Wat Phananchoeng Pier. The fare depends on the route and duration. Rice barges are also available for groups that offer a relaxed way to see Ayutthaya.