The Cryobank grew out of a simple idea for repurposing the spawn tube prop as a cryonics chamber. It grew into a large fortress with a lot of verticality and alternate routes. The terraced levels of the Cryobank overlooking the road promote the infantry and vehicle siege combat between attackers and defenders, and the number of routes into the facility prevent it from being an easy hold on high ground.
This base is particularly special to me because I watched it playtest for a about 24 hours over a 3-day period during E3 2014. It was chosen as our base for our demos for the PS4 version, and we created a special variant that had static spawn points in approximate Sunderer mobile spawn locations. Playtesters (The PS2 development team, QA & CS) back at the office took shifts making a fight at the Cryobank during show hours and took it easy on the demo station characters to let the press look at something other than the death screen.
Early on, demos were full of warning shots, multi-second handicaps before firing and intentional whiffs to give people on the floor a good chance to look around. As time went on, these playtesters have put in 10-20 hours of running around in circles pulling punches and making bullethole angels around players; it can be pretty dry stuff. By Day 3, the show turned into a combination demo derby / airshow where buggies would slam their turbo on the lip of the bridge, sending them spinning onto the lower terrace through a dozen soldiers. Overhead, reavers are flying upside down through valleys on each others tails and midair collisions send two interlocked fighters sailing into an antenna tower. Players absolutely loved the chaotic spectacle that the couple dozen playtesters had put on, mimicking the bedlam that large fights often have.
Granite Valley Garrison was designed primarily around putting the tower in a valley, reducing its height advantage and increasing its vulnerability against aircraft. While resecuring points is easy due to their proximity to the tower as well as the bridges leading defenders there, aircraft will effortlessly clear the streets if sufficient anti-air isn't present.
Keeping this outpost lies heavily on whether or not the defender is able to keep a healthy ecosystem of infantry on the airpads, the highest accessible point to most classes. The valley has few points that aren't visible from up there, and they overlook the two entrances into the core of the base. If the defenders keep engineers, anti-air MAXes, countersnipers and a medic or two up there, it's easy to keep a bigger force at bay.