About 10 years ago my partner and I were in Eclectic Games in Reading looking for a game to buy. Some friends had recently got us into playing mdern boardgames via Ticket to Ride and Merchants of Venus, while our usual gaming was Scrabble or UpWords (you marry an author, you play word games).
The man in the shop suggested two games - Ascension (which I'll get to another day) and Carcassonne.
For three years we played Carcassonne at least twice a week. For us it was a perfect two-player game - easy to learn but with possibilities for complexity. A great mix of luck (the tile you pull out of the bag) and skill (where to place it) with opportunities to be quite vicious if the mood takes you.
A mid-game view - red is busy but yellow is winning due to some fine city building and acrobat play. They've also had the big top in their area more often than redAnd the expansions! I went a bit crazy on the expansions and bought the first six expansions and a bunch of mini-expansions until we ran out of space on the table in our apartment.
Suffice to say we over-played the game and after three years I never wanted to play the damn game again.
Then last year I was in a games shop and they had another expansion - on a circus theme. My wife like circuses so, I bought it. A couple of weeks ago I plucked up courage and we opened the big top box...
For those who don't know the game, 
The game involves placing tiles to create a landscape and adding wooden counters (meeple) to score based on size of city, length of road, tiles around a cloister and number of cities served by a farm. The expansions allow all sorts of additional geography and meeple types.
We kicked off with a basic starter-set of 72 tiles and 8 meeple each.
It was a pleasure to play again. Establish your farm; get those roads up to set borders to avoid farm wars and keep those cities small for maximum points! The tactics came back quickly - watch out for stray bits of field which could link to your farm and nullify your points if claimed by the other player (farm wars can escalate quickly and lead to a shocking waste of meeple life). Group your cloisters for maximum efficiency. Junction that road to steal a bunch of points.
After a couple of base games we brought on the elephants.
Flea circuses are not big winnersUnder The Big Top introduces three new scoring options:
The Big Top is placed on circus tiles, with a round counter underneath it. When the next circus tile is placed the big top moves there and the counter on the previous is flipped. The value of the counter is then awarded to every meeple in a square around the circus tile.
Yellow scoring three points for a big top. If they leave the acrobats there until the big top moves again, they'll get three times the points shown on the counterThe Ringmaster acts like a normal meeple, but when his city/road/cloister is completed he scores an extra two points for every circus tile next to him.
The ringmaster on the right will score road points when his road is complete, plus 2 points for the acrobat tile nearbyAcrobat tiles allow you to create a three-meeple pyramid when you place tiles next to them (creating meeple pyramids is a traditional between-turns activity). Once the pyramid is complete, any player can score it, and each meeple in the pyramid gives its player 5 points. Pyramids can feature any colour of meeple, but experience has shown that they seldom mix as you seldom place tiles for different players together in a 2-player game.
Red about to score 15 points for their acrobatsAll three options are quite interesting and do impact how you play. The big-top especially as it's not worth completing features around it as you would lose potential points if your meeple aren't in place to be scored. The acrobats score well but tie up your pieces sometimes for several goes.
Overall, though, the points gained seem disproportionate. Adding the expansion to the base game doubles the number of points scored in a game, but without doubling the interest as regards new geography.
This Under The Big Top expansion is better than some, but still not as good as the first two (Inns and Cathedrals and Bridges, Castles & Bazaars).
We think it will work better if there's more expansions in the game, so the occurrence of the tiles is watered down.
Since playing the expansion, we've spent another evening playing Carcassonne, but gone back to the early days with The River and Inns and Cathedrals. We can manage three games and a bottle of wine for a great evening's game playing.
The expansions reduced to one line summaries
Inns and Cathedrals is the initial expansion, and the Cathedrals are a must-have.
The River expansions definitely make the opening of the game more interesting.
Bridges, Castles & Bazaars is my wife's favourite for the bridges - she gets a lot of mileage out of them.
The Tower is my wife's least favourite expansion, because I get a lot of mileage out of the towers :0)
The Princess and the Dragon is fun but the dragon doesn't really fly with two players.
Traders and Builders doesn't add much other than more complex scoring options.
Abbey and Mayor is okay - the abbeys are cloister cities which can be useful
Count, King & Robber aren't too interesting.
Wheel of Fortune adds an additional random element via a spinner and forfeits but messes up the opening by having a 6x8 start tile. One to avoid unless you don't find the normal game random enough.
We gave "The Catapult" a miss, and didn't know about "Hills & Sheep" until I just looked up all the expansions for this list.
Other game reviews:
Ion: A Compound Building Game
Thunderbirds Board Game
Covalence: A Molecule Building Game
Hangry Blobfish From Mars Card Game
Subatomic: An Atom Building Game