Depending on the application most large free standing towers are constructed using steel lattice design. This type of tower is popular as it provides great strength at a low weight with great wind resistance properties and is economically cheap in terms of the materials used. Although triangular cross sections are the most common square lattices are also widely used. These towers can be parallel sided or taper as they rise.
Independent towers also come in many other forms such as monopoles (popular as base stations for cell networks), tubular steel towers, reinforced concrete, and serviceable or hinged masts. In remote locations towers are often selected on their RF performance and costs alone however in urban or developed areas aesthetics often become a consideration. It is common to try and disguise towers and or use designs that don't draw unnecessary attention to them. Sometimes using 2 smaller towers (especially if they are identical/symmetrical) can produce a more visually pleasing result than one large tower.
Other considerations when evaluating tower designs include: access for riggers, which is often dictated by the maintenance schedule for the structure as well as the frequency which the mounted RF needs to be accessed. Aircraft warning features, day warning strobes and night warning lamps as well as the associated light pollution. Height restrictions that are imposed due to legislation by relevant bodies. Environmentally harsh conditions such as areas where ice buildup is a concern and high winds that can produce wind-induced oscillations which particularly affects the performance of directional antennas with narrow beamwidths.
Whether a single tower to provide a small private property with improved cellular communications or a huge microwave repeater/junction for long range transmissions free standing towers are ideal where real estate is at a premium and a small footprint is a priority (making the use of guy wires as unacceptable) or where the terrain is particularly challenging such as remote, mountainous, densely forested and hard to access locations. Investing in tower infrastructure can provide solutions to RF signal issues and long term returns.
Due to the complicated nature of tower infrastructure it can prove extremely valuable to have an engineer approved recommendation for a solution that will accommodate a particular project. Telco offers a Tower Recommendation Proposal Consultation Service, this provides the customer with a report that can be used for planning of communication assets.